PRELIMINARY CONDITION SURVEY

CASTLE ACRE PRIORY PRECINCT WALL

JOHN SELBY BA MSc IHBC Conservation Planning Design Training

27th May 2011

CONTENTS

Summary and Recommendations

page 3

Introduction

4

Status

4

Condition Survey Section 1: Gatehouse to Priory Road

Section 2: Priory Road west Section 3 Priory Road east to Abbey Cottage

Section 4: Abbey Cottage Section 5 South Acre Rd from Abbey Cottage to Chimney St

Section 6 South Acre Rd from Chimney St to wet ditch Section 7 wet ditch to riverside bend in the road

Section 8 alongside the River Nar Section 9 west of the Priory ruin5

5 6

10 13 17 19 23 26 28 36

Vegetation Management

37

Rabbit Control

38

Repair Principles

39

Recording

40

Phasing & Public Safety

40

2

SUMMARY & RECOMMENDATIONS

This report is a preliminary survey of the precinct wall in its current state. To assist this, the wall has been divided into sections (see page 5) and each section is then described in terms of dimension, materials, vegetation growth, animal damage and general condition.

Each section report has a summary of work required. Suggestions for vegetation management and rabbit control are made

(pages 37-38). A decision is required at an early stage concerning the level of

vegetation removal. An overall aim or vision could involve the eventual removal of vegetation from all standing masonry and the earth capping of banks where masonry is low or not visible.

Before this decision is made, it is recommended that the public be fully informed of the issues and engaged in the project. The Parish and Borough Councils need to be involved also.

If vegetation is removed from standing masonry, a photographic record should be made before repair work begins.

There are public safety issues in sections 5 and 6 (South Acre Road) and section 8 (near the ford).

A phased programme is given (page 40), commencing with the areas where there are safety issues.

Principles for repair are given on pages 39 and 40. A regular programme of future maintenance is also suggested.

3

INTRODUCTION The purpose of this preliminary survey is to record the full length of the precinct wall to Castle Acre Priory in its current state, to provide a general statement of condition in order to inform repair work and vegetation management. The survey was carried out between the 11th and 18th April 2011. Ground vegetation was low and trees had not come into full leaf. However, sections of the wall were still obscured by ivy and bramble growth and in places were difficult to record.

STATUS The substantial remains of the Cluniac Priory at Castle Acre are of national significance and form a scheduled ancient monument (no. 21416). The priory gatehouse and the priory remains are listed, grade I. The precinct wall is within the area scheduled and forms the boundary of the ancient monument. Though not listed, the precinct wall is within the curtilage of the priory buildings. Abbey Cottage, which is sited at the north-east corner of the wall, is listed, grade II and is within the scheduled monument. The whole of the precinct lies within the Castle Acre Conservation Area, which was designated in 1971 (the first in Norfolk) and was extended to include St James’s Green in 1990. The Castle Acre Conservation Area Character Statement was revised in May 2009. There are no tree preservation orders on any of the trees along the length of the precinct walls, nor within the monument itself. However, as the site lies wholly within the conservation area, the local planning authority will need to be informed beforehand of works to top, lop or fell trees.

4

CONDITION SURVEY

432

5 1

Numbered Survey Sections of the Wall

6

9

8

7

The precinct wall has been divided into sections for survey purposes as shown above. Each section is subsequently described and illustrated below. Within the report, the term inner face refers to the wall facing the field and outer face to that facing the road or river.

5

Section 1

This section of the precinct wall runs from the gatehouse northwards to Priory Road. On its inner face it comprises a low bank, earth capped with some flintwork exposed on top. On the outer face, facing the access track to the monument, the wall is partly an earth capped bank but there are sections of flint wall standing.

Dimensions This is a 57 metre section. It is a low bank on the inner face and varies in height on its outer face between 62cms, at its junction with the gatehouse, to 140cms at the ash tree (30metres south of the NW corner). Elsewhere where standing masonry survives, it is at around 1 metre in height. Masonry width is around 140 to 150cms. Materials On its inner face, it presents a low bank of flint mostly earth capped. On the outer face it runs as an earth bank, without exposed flint, from the northwest corner (Priory Road) south, past the lavatory block, for around 20 metres to a tall beech tree. Behind the beech a wall of flint rises to about a metre. The random flints are crudely coursed and set in a hard mortar with relatively wide joints (a repair). Further south (approximately 30metres from the Priory Road corner), where a tall ash tree grows out of the top of the wall, the masonry rises to 140cms. It is also of un-knapped flint in a hard mortar, with joints of 3 to 4cms. The size of flints varies from around 12x10cms to 8x6cms to 6x6cms and many flints have a chalk ‘rind’. There is evidence of capping in hard mortar (probably cement), but this has broken up in places. From just beyond the ash tree southwards, it continues as an earthen bank and then a low section of wall 62cms high and about 80cms thick joins the gatehouse. This small section of wall has similarities with the gatehouse. There are three courses of red brick exposed at the base and above, flint rubble, some knapped, in lime mortar shows signs of galetting, as seen in the gatehouse.

6

Gatehouse

1. Outer face, junction with gatehouse

Vegetation On the outer face there are signs that vegetation has been cleared from the wall, but ivy is regenerating and new elder sprouting. The wall is separated from the track by an area of grass with celandines and some trees in it. A tall beech tree is situated close to the wall and its roots run into it. But of greater concern are the trees and bushes growing on top of the wall, including a tall ash, several hawthorns, elder and blackthorn. Much of the earth bank is obscured by ivy and there is bramble also, especially near to the gatehouse. On the inner side, the field is pasture with patches of nettle, thistle and speedwell. There are large patches of nettles close to the wall and some wild flowers, including white deadnettle, hedge garlic and wild arum. Much of the top of the wall is covered with ivy.

2. Outer face bank running north to WC block 3. Inner face: NW corner masonry, ivy &

nettles Animal damage The precinct walls contain a veritable warren of rabbits, which have chosen the edges of the field, along the base of the walls, as their preferred location for burrows. The extensive cover of nettles near the walls hides the burrows and provides a trip hazard.

7

Rabbit damage in Section 1 is perhaps less significant than in other stretches of wall (see Section 2 for example). Yet they are burrowing close to the wall and actually burrowing underneath in the vicinity of the gatehouse.

4. Rabbit hole at gatehouse corner

There are mole hills within the field, but no evidence of damage. General condition The wall in Section 1 is in fair condition and has clearly been maintained on its outer face, where vegetation has been cleared relatively recently and longer ago, attempts were made to provide a cement cap and bulges were consolidated. Yet cement is not to be recommended with flint and the cement cap is now fragmentary and flints are coming loose. Much of the wall has an earth cap, particularly where it is now a bank. Wall 30metres from north end

5. Repair with cement mortar 6. Ash growing on top of wall and cement cap

Vegetation is growing on and around the wall, particularly on its inner face. At 30 metres from the north end, a sizeable ash tree is growing on top of the wall and its roots have caused the wall to bulge on the outer face. At around 50 metres from the north end there is a hawthorn tree and a small elder and then

8

at 52 metres, another hawthorn with ivy at 53metres. All of these are growing on top of the wall.

cement repair hole where facing flints have fallen out

7. Outer face below ash tree. Elder, rose, bramble and ivy grow alongside the wall on both sides and have begun to regenerate where they have been cleared on the outer face. The large beech tree situated close to the wall on the outer face has probably done as much damage as it can and the consequences have been repaired. It no longer poses a significant threat, nor do the other ornamental trees alongside the priory track. There is an area of undercutting at the base of the wall behind the beech tree.

8. Undercutting at base of wall near beech tree

There are extensive rabbit burrows amongst the nettles. Work required

Remove vegetation growing in the wall. This will involve the felling of the ash tree as well as the removal of hawthorn, elder, apple and ivy. The removal of roots from within the wall would cause more damage than simply leaving them, cut flush with the wall surface, growth being controlled by painting the stump with a glyphosphate-based herbicide.

Repair flint face below ash tree (see photo 7) using lime mortar and flints laid in courses with narrow joints.

Restore base of outer face behind beech tree (see photo 8). Remove loose cement capping and replace with feeble hydraulic lime

mortar. Provide soft earth cap to top of bank where masonry not exposed. Control rabbits and fill-in burrows running under and along the wall.

9

Section 2

This section of the wall runs from the northwest corner eastwards along Priory Road to a gap opposite the entrance to the coach depot. The gap gives a fine view down to the priory. The outer face runs along the top of a roadside bank and the inner face comprises a masonry wall of around 2metres in height.

Dimensions This section runs some 34 metres eastwards, forming part of the north side of the precinct. On the inner face, the wall rises to approximately 2 metres in height with gaps. At 14 metres east of the northwest corner, it rises to 3metres. The east end of the section is a gap, some 6metres wide, where it forms a bank about 1metre above the level of the field. The width of the wall is around 80cms.

9. The gap looking out to coach depot 10. looking in towards the priory remains

Materials The northwest corner of the wall is completely covered by ivy, but appears to be a flint structure rising up to 2 metres above the top of the roadside bank. A splayed section of flint links it to Section 1 (see photo 3 above). The wall runs on top of the roadside bank eastwards, but masonry can only be glimpsed amongst vegetation.

11. Coursed flints with narrow joints on the inner face

10

The wall is particularly visible on its inner face, where sections rise to 2 metres in height. It is of small flints of irregular shape and not knapped, though some flints have broken faces. The flints are laid in courses with narrow, recessed joints. The mortar is lime rich and contains course sand particles. Vegetation The outer face is covered by vegetation, much of which actually grows in the masonry. Ivy, elder and hawthorn predominate, together with bramble. The grassy roadside bank has bushes growing on top of it and where masonry has fallen, there are views through to the priory ruins. There are some substantial growths of ivy.

ivy stem

12. Large ivy stem growing from base of the inner face (20m east of NW corner)

Animal damage There is a large rabbit warren on the field side and burrows extend up to and under the wall. The wall foundations have been exposed, notably at 14 metres east of the northwest corner, where the wall rises to a height of 3 metres. There is some evidence that grazing animals, seeking the shelter of this northern wall, have helped expose the foundation.

13. Rabbit burrows and ‘shelter’ for sheep 14. Foundation exposed where burrow runs under

the wall (The wall here is 3 metres high)

11

General condition There are gaps in the masonry at 4 metres east of the corner and at 11 metres a section has fallen into the field.

gap 11m east of corner

fallen masonry on field side

15. Gap and fallen flints at 11metres On the field side, the masonry seems in reasonable condition, though there are a few loose and fallen flints. The top of the wall is generally concealed beneath vegetation, but where it is possible to see, it appears to have been capped with cement. The collapsed flintwork at the gap, forming the eastern end of this section of wall, lies in the field covered in earth. The remaining wall is about a metre above the field level and also earth-capped (see photographs 9 & 10 above). Work required

Provide ‘soft’ remedial foundation to areas where foundation is exposed, using well-compacted crushed chalk.

Consolidate loose flints and replace individual flints which have fallen, using lime mortar and salvaged flints where possible.

Carefully remove vegetation growing on the wall and young scrub growth alongside it. The removal of roots from within the wall would cause more damage than simply leaving them, cut flush with the wall surface, growth being controlled by painting the stump with a glyphosphate-based herbicide.

Remove loose cement capping and replace with feeble hydraulic lime mortar.

Provide soft earth cap to top of low masonry where there are gaps in the wall.

Control rabbits and fill-in burrows running under and along the wall. Maintain inner fence to restrict access to the wall by grazing animals.

12

Section 3

This section of wall runs east from the gap opposite the entrance to the coach depot, alongside Priory Road to the electricity substation. As in Section 2, the outer face runs along the top of a roadside bank and the inner face comprises a masonry wall of around 2 metres in height, but with a number of gaps.

Dimensions The section is approximately 100 metres long, running alongside Priory Road and forming, with section 2, the northern edge of the precinct. The section starts from the gap opposite the entrance to the coach depot and runs eastwards. The gap is about 8 metres wide. To the east of the gap, on the inner face, the wall rises initially to a height of 140cms and then beyond up to 2 metres. This tall stretch of wall runs for some 6 metres before it is breached by a gap. It then continues rising to almost 3 metres, before dropping to a bank of about I metre in height and it continues as such to the east end of the section, apart from a 2 metre stretch (located 80 metres east of the start of the section), where it rises to 2 metres. This section then is characterised by tall stretches of masonry on the inner face interspersed with gaps. On the outer face, much of the masonry is hidden by vegetation, whilst gaps afford views down to the priory ruins. Where standing masonry survives, the wall is about 80cms thick. Materials The wall is composed of coursed angular pieces of flint, (40cms x 20cms at the base and around 6cms x 11cms near the top), much the same as section 2. Some flints have broken faces and many have a chalk ‘rind’. At 16 metres east of the start of the section, part of the core is exposed, which is of flint rubble in lime mortar with a piece of chalk within it. The chalk block is approximately 24cms x 12cms in size.

13

knapped flint

chalk block

16 & 17. Flintwork to inner face and exposed chalk at 16 metres east of start of section Vegetation Much of the wall and bank have vegetation growing within them, including some substantial trees and bushes. At 10 metres east of the start of the section, a large ash tree grows from the side of the wall and at 16 metres there are hawthorn and sash growing on top of a 2 metre high section. At 36 metres there is a very large ivy above a stretch of wall which has been undermined, at 40 metres hawthorn and elder grow on top of the wall and at 49 metres an ash tree fills a gap.

18. Large ash tree at 10 metres 19. Ash growing in gap at 49 metres Animal damage From around 24 metres east of the start of this section, travelling eastwards to its end, where it meets the electricity substation, there are extensive rabbit

14

burrows and beyond the ash tree shown in photograph 19 above, the wall runs as a rabbit damaged bank.

20. Rabbit damage, undermining base of wall at 3 metre high section

General condition Where tall sections of masonry survive, the wall is fairly vertical. The main problems affecting its condition are undermining by rabbits (described above), loose flints, exposed core material, which is liable to crumble with frost action, and the loosening of capping material by tree and bush roots. From 49 metres west to the section end, the wall is a rabbit damaged bank capped with bushes and at 80 metres fly tipping has occurred. Where the top of the wall is visible, it can be seen to have been capped in cement, which is breaking-up. A particular problem occurs at 24 metres, where the upper sections of flint to this 3 metre high stretch have become loose and are in danger of falling. This same section has exposed core in places and is being undermined by rabbits (see photograph 20 above and 21 below).

21. Crumbling flintwork at high level on inner face

15

Work required The extent of the damage to the cap and to flintwork at high level can

only be assessed if vegetation is removed. Where flints are falling or where they have fallen out, they should be

reset or replaced (using salvaged flints where possible) in a lime mortar Where core material has been exposed, the facing flintwork should be

reinstated with matching lime mortar, coursing and joints. Carefully remove vegetation growing on the wall and young scrub

growth alongside it. The removal of roots from within the wall would cause more damage than simply leaving them, cut flush with the wall surface, growth being controlled by painting the stump with a glyphosphate-based herbicide.

Remove loose cement capping and replace with feeble hydraulic lime mortar.

Provide soft earth cap to top of low masonry and where there are gaps in the wall.

Control rabbits and fill-in burrows running under and along the wall.

16

Section 4

This section runs along the roadside boundaries of the electricity substation and Abbey Cottage house and garden. It includes the northeast corner of the precinct wall, where it turns the corner and runs south down South Acre Road. The wall is a bank with flintwork exposed in the foundations of Abbey Cottage.

General condition and description It is unfortunate that when the substation was constructed on the inner side of the wall, the access to it was driven through the earth capped bank of flintwork which comprises the precinct wall here.

22. Breach in bank at substation entrance

Abbey Cottage

23. East gable on roadside bank 24. C15 flushwork above flint plinth

17

Abbey Cottage, which comes next, is a grade II listed building within the scheduled monument site. It is in private ownership. It comprises a flint and stone rubble building with limestone quoins and the remains of flint and limestone chequerboard flushwork in its east gable. This section of the building probably dates from the fifteenth century. In the nineteenth century it was extended in red brick westwards and was further extended to the west, also in red brick, in 2009. The fifteenth and nineteenth century sections have flint foundations along the line of the precinct wall. It is likely that the wall itself was used for these foundations.

25 North elevation & west extensions in brick 26. Flint foundation to C19 extension To the south, along South Acre Road, the garden sits behind a wooden fence on top of a high roadside bank, probably along the line of the precinct wall.

. 27. South Acre Road looking north to Abbey Cottage

18

Section 5

This sections runs southwards down South Acre Road from the end of Abbey Cottage garden to a linear depression, just to the north of Chimney Street. There is a gap in the wall at the south of the garden fence, which is used as a path into a copse. For much of the section, masonry occurs at a high level above a sunken lane.

Dimensions This section is approximately 100 metres in length. On its outer (roadside) face it runs as a high bank around 1.5 to over 2 metres with some masonry on top. On the inner face, the wall is occasionally exposed, but its northern section runs as a bank almost flush with the ground level of a sycamore copse (a former tennis court). There is a gap in the wall here, which is used as a path into the copse, which is fenced off from the field to which it is linked by a metal gate.

28. Entrance to sycamore copse and start of section 5

Materials The wall is composed of coursed angular pieces of flint, much the same as sections previously described. Some flints have broken rather than deliberately knapped faces and many have a chalk ‘rind’. Vegetation At the northern end, next to the garden to Abbey Cottage, there is a sycamore copse (which has grown in a former village tennis court) and along the whole length of the wall from north to south, it is covered with vegetation with a number of mature and semi-mature trees growing in it or close to it. A

19

number of these trees have root systems which run laterally, close to the top of wall masonry.

Mature vegetation on top of wall

29. Looking north up South Acre Rd, near Chimney St 30. Looking north beyond bend Animal damage Within the sycamore copse at the north end of the section, the ground level is almost flush with the wall. On the outer face, the wall is vegetation covered on top of a high bank, with South Acre Road running as a sunken lane. The copse appears to have been used as a tip and there are rabbit holes close to the wall, which is high above the road.

31. View of wall from within the copse showing flush ground level

and sunken lane beyond with the churchyard across the road General condition Although little of the wall is visible, its condition causes concern. The first 50 metres or so run along the edge of the copse. The wall is flush with the ground level and acts as a retaining wall to the sunken lane below (see photograph 31). Young saplings grow close to it and rabbits are burrowing close to its edge.

20

To the south of the copse on the inner face, the ground level drops and the wall is expressed as a low bank, less than a metre high, with loose flints on top and bushes and trees growing out of it. Beyond, the wall is completely covered with dense bramble. At 75 metres from the north end, a large chunk of masonry has been dislodged by trees and has fallen onto the roadside. The chunk of masonry has been consolidated with cement mortar (as presumably much of the top of the rest of the wall) and the roots have undermined the softer lime mortar beneath.

32. Fallen masonry on roadside 33. Detail of fallen masonry showing cement mortar The situation could easily be repeated and there are clear public safety issues here. At 82 metres a row of tall trees show roots running close to the top of the wall and there is much loose flintwork. All this on top of a high bank above a sunken lane.

34. Tree roots affecting top of the wall along a high roadside bank

21

Work required

Remove vegetation growing in the wall. This will involve the felling of trees as well as the removal of bushes, bramble and ivy. The removal of roots from within the wall would cause more damage than simply leaving them, cut flush with the wall surface, growth being controlled by painting the stump with a glyphosphate-based herbicide. As the roots left within the wall shrink with time, consolidation will be necessary.

Remove woody vegetation and sycamore saplings growing near to the wall in the copse at the north end of the section.

Where the masonry acts as a retaining wall alongside the copse, consideration should be given to the provision of ‘weep holes’ in the wall.

Remove loose cement capping and replace with feeble hydraulic lime mortar.

Provide soft earth cap to top of bank where masonry not exposed. Control rabbits and fill-in burrows running under and along the wall,

particularly in the sycamore copse.

22

Section 6

This section runs south downhill along South Acre Road, from the linear depression, north of Chimney Street, to a wet drain. At 224 metres from the northern point of this section, an informal path crosses the wall and forms a route from the road to the priory. As in Section 5, the north part of the wall stands high above the sunken lane, but the southern section is largely a low bank.

35. Section 6 inner face looking north to the linear depression

which separates it from section 5 beyond Dimensions This stretch of wall is 270 metres long. For the first 40 metres or so, the wall is low, some 55cms above field level, but high above the road. It then runs as a low bank until at 196 metres, masonry reappears, rising to nearly 3 metres for a short stretch (at 220 metres), where it is 70cms thick. At 224 metres it becomes a very low bank and stays at a low level to the southern end of the stretch. Materials Where masonry is exposed, it is of coursed flints up to 23 x 20cms, many with chalk rind and some are broken, rather than deliberately knapped. The flints are in a lime mortar with narrow joints. Loose flints appear on top of the wall where it runs as a bank. Vegetation Photograph 36 below shows the outer face of the wall running south from Blind Lane. This is typical of the stretch; covered in shrubs, ivy and bramble, obscuring masonry where it survives or covering an earth capped bank.

23

There are a number of trees growing in or close to the wall, as, for example the ash tree shown in photograph 36, which is at 196 metres south of the start of the stretch.

36. South Acre Road looking south with vegetation and mature ash tree on the wall.

Animal damage Although they are present, rabbits seem to be less of a problem in this stretch. There are some burrows close to the wall and at 98 metres south, a hole runs into the wall.

burrow

37. Rabbit burrow in the wall General condition Rather like section 5 described above, there are lengths of this wall on the northern stretch which are high above the highway. Although completely covered by vegetation, there are areas where sections of flints are loose and likely to fall towards the road. The public risk is probably not as high as section 5.

loose flint above the road

37. & 38. Low wall on inner side with loose flint hanging high above the road

24

At 220 metres south of the start of the stretch, a short section of masonry rises to nearly 3 metres and is entirely covered by ivy. The flintwork is generally sound and the wall is fairly vertical.

39. Flint wall 3m high beneath ivy

South of this point, the masonry virtually disappears and the wall becomes a bank with occasional flints visible on top. Bushes and small trees grow on top of it for much of its length. Work required

The extent of the damage to the cap and to flintwork at high level can only be assessed if vegetation is removed. Indeed the extent of surviving masonry can only be assessed if vegetation is cleared.

Where flints are falling or where they have fallen out, they should be reset or replaced (using salvaged flints where possible) in a lime mortar

Provide soft earth cap to top of bank where masonry not exposed. Control rabbits and fill-in burrows running under and along the wall.

25

Section 7

This stretch runs from the drain to just beyond the bend in South Acre Road at its south end. At this point the road turns a right angle bend to follow the River Nar. The wall is a low bank and disappears altogether near the road corner.

40. The drain marking the start of the stretch 41. Looking north up South Acre Road Dimensions This stretch is 74 metres long. For much of its length, the wall has become a low bank with crumbling flint on top and covered with vegetation. At 74 metres south of the drain, close to a field corner post (see photograph 41 below), the wall disappears and there is no wall where the road turns its right angle bend.

42. Field post beyond which the wall disappears

26

Materials Loose flints are visible on top of the low bank running alongside the field ditch on the inner face.

43. Celandines in the field ditch with loose flints on the vegetation covered bank

Vegetation Alder, hawthorn, hazel, elder, blackthorn and spindle grow along this stretch with ivy and bramble. There are ash trees close to the bend in the road. The vestiges of wall along this stretch have already been affected by vegetation and it is arguable that the flora is now more significant than the precinct wall Animal damage Minimal. General condition For much of this section there is no sign of the wall, which may have been destroyed when the highway was constructed alongside the present course of the river. Where vestiges survive, they are expressed as an earth bank, very low in height and completely covered by a good mix of bushes and trees. Work required

This section is possibly best left alone or if woody vegetation is removed from the remains of the bank, it should be earth capped. However, the removal of bushes and trees here is likely to have an impact on the ecological interest at a point where the vestiges of wall meet the important wildlife corridor of the River Nar.

27

Section 8

This stretch forms the southern boundary of the precinct wall. It follows the winding course of the River Nar until the wall peters out. This section of the Nar is a popular place for paddling and fishing, particularly near the ford. The footpath following the inner face of the wall is also well used. The wall comprises stretches of standing masonry with gaps and to the west it gradually peters out.

Dimensions This stretch is approximately 300 metres long and runs west from a section of standing masonry a short distance from the bend in the road. It comprises a series of wall fragments separated by flint topped banks and then, at its western end, it becomes a grassy bank which gradually disappears. Where this section meets section 7, there is a ditch running alongside the road, but without any signs of the wall.

44. Ditch and no signs of wall at the start of the section

Beyond (27 metres from the section start) is a stretch of masonry, some 16 metres long with two small gaps in it. It leads to wide gap in the wall near the ford, where there is a public bench and litter bin either side on the outer face. It stands about 2 metres high and is 43cms wide at the base and 33 metres at

28

the top. At the east end it is set at an angle to the road and at its west end, where it meets the gap at the ford, it rises to 2.5 metres

Outer face

45. Looking east from ford 46. Looking west to ford Materials Where standing masonry occurs, it is composed of coursed flints of random size set in a lime mortar with narrow joints. The upper parts of most of the visible masonry have been cement capped.

47. Flint cobbles to outer face on 48. Coursed random flints at 14m west of the gap east side of the ford gap At the gap in the wall close to the ford, core material is exposed below a cement cap. The core material is soft lime with flint fragments and there is some repair using a cement mortar in an attempt to consolidate the masonry. The gap at the ford is about 2 metres wide and provides access into the meadow across a low bank with loose flints on top. It is an informal, but much used access and there is a litter bin and bench on the outer face, either side of the gap.

29

litter bin gap

49. Public access gap near the ford Behind the litter bin, the masonry is just under a metre high. Some ten metres from the gap westwards, there are fallen sections of masonry in the path and then, 14 metres to the west is a 3 metre section of leaning wall rising to 2.6 metres in height and some 70cms wide. Beyond to the west the line of the wall forms a grassy bank for 20 metres and gradually peters out. Beyond masonry occurs at 80 metres west of the ford gap, where a stretch is divided into two by a gap, leaving a 3 metre section, 1 metre high on the east and a 2 metre lower stretch to the west – all about 35cms wide. Beyond this point, there are no further sections of masonry and a low riverside bank gradually peters out. Vegetation The eastern end of this section, around the right angle bend in the road, is characterised by trees, bushes and bramble wit little sign of the wall. Flora and wildlife interests in this 27 metre stretch are probably of greater importance than the wall and vegetation removal is not necessary (see photograph 44 above). Similarly, at the western end of the section, where the wall forms a tussocky grass bank and then a bush topped lower bank before gradually petering out, vegetation could be left undisturbed.

Grassy bank 80m west of the ford gap

50. Looking east to leaning masonry 51. Looking west where wall peters out

30

However, where masonry occurs, it is invariably clad in ivy with hawthorn and bramble (see photographs 53 to 56 and 61 below).

52. View along the River Nar eastwards towards the ford

Animal damage Animal damage is not a significant problem along this section of wall. General condition Masonry starts some 27 metres from the east end of the stretch, where there is a section of ivy-clad wall, which stands almost 2 metres high and set at an angle to the road. This runs eastwards for 16 metres with two gaps in the masonry until it reaches a wide gap near the ford, where the public bench is situated. This section of wall is for the most part in reasonable condition, but is entirely clad in ivy with hawthorn and bramble, which needs to be removed.

Section of masonry with gaps at 27 metres running to the gap near the ford

(Inner face)

gap to ford

53. East end of wall 54. Two gaps in centre 55. West end of wall

31

Loose flints need replacing and when vegetation is removed, the cap may require consolidation. The removal of vegetation at the base of the inner face may also reveal some undercutting, but it is the west end at the ‘ford gap’ which causes concern. Here the wall has become top heavy and attempts to consolidate using cement rich mortar have exacerbated the problem. Flintwork below the cement cap has eroded and core material has been exposed (see photograph 55 above). Although the masonry seems fairly stable at the moment, frost action will undoubtedly cause further erosion and in time the cap will fall. The wall leans towards the road and there are loose flints on top beneath the ivy.

56 Top heavy section of wall leaning 57. Loose flints at top of the wall towards the road and ivy clad

The gap in the wall which follows to the west provided access to the meadow and is well used by the public. Indeed the ford area is a popular picnic spot. The condition of the wall at this point gives cause for concern in the interests of public safety.

58. The ford and top heavy masonry to the left.

The gap itself is a low bank with loose flints on top, eroded by its use as a public access. Beyond a footpath continues westwards, following the inner

32

face of the wall. Loose flints strew the path and at 10 metres west of the ford gap, a piece of flint masonry has fallen (some time ago) into the path.

59. Footpath with strewn flints west of 60. Looking east to the ford gap the ford gap. with fallen masonry in the path Just beyond the fallen flintwork (14 metres west of the ford gap) a section of wall, leaning southwards towards the river, rises to 2.6 metres and is 70cms wide. It leans some 30 degrees from the vertical and the base has been consolidated with cement mortar.

61. Leaning masonry 62 Consolidation of leaning masonry

Indeed, were it not for the dense ivy and bramble supporting it on the south side, it would topple. Shoring needs to be considered.

33

Westwards beyond the leaning section of masonry, the wall is a low bank covered with tussocky grass (see photographs 50 and 51 above). This runs for some 20 metres and then continues close to the river as a very low hedge topped bank with no masonry visible. Then, some 80 metres west of the leaning wall is the final section of standing flintwork, close to the river and divided into two short sections with a hawthorn tree growing on the south (river) side. There are also fragments of masonry on the riverbed at this point.

63. Final section of standing masonry 64. Fragments of flintwork in the river with thorn tree

The section behind the hawthorn leans slightly towards the river and its top is of lime mortar. The lower section to the west has been capped with cement. Both sections seem stable, though the taller (eastern) section has been affected by the hawthorn. From this point westwards the wall seems to have petered out and may have disappeared in the river. There is a riverside bank, but no discernable evidence of the wall. Work required Where standing masonry survives:

Leaning and top-heavy masonry in this section poses a public safety problem. At the ford gap, public access needs to be controlled by providing a gate and/or stile in the vicinity of the litter bin away from the top-heavy masonry. This latter section of flintwork needs to be consolidated and stabilised. (Shoring or buttressing may need to be considered).

34

The line of the footpath within the precinct wall could be re-sited further away from the river if the current wire fence was also re-sited. This would prevent further erosion of flintwork, which could be earth capped here.

The section of leaning masonry is supported by ivy and bramble, so long as the vegetation survives or until roots cause gradual collapse. It is likely to fall eventually in the direction of the river. Shoring or buttressing should be considered and consideration should also be given to the removal of vegetation.

Generally, vegetation growing on the wall and young scrub growth alongside it needs to be carefully removed. The removal of roots from within the wall would cause more damage than simply leaving them, cut flush with the wall surface, growth being controlled by painting the stump with a glyphosphate-based herbicide.

The extent of the damage to the cap and to flintwork at high level can only be assessed if vegetation is removed.

Where flints are falling or where they have fallen out, they should be reset or replaced (using salvaged flints where possible) in a lime mortar and where core material has been exposed, the facing flintwork should be reinstated with matching lime mortar, coursing and joints.

Where the wall is a vegetation covered bank:

Consideration should be given to the removal of ‘woody’ plants and bushes. Otherwise it should be left alone.

35

Section 9

This short section is situated north of a group of ‘commercial’ buildings which are sited southwest of the main claustral ruins. It runs along a track, meeting a more recent boundary wall to the priory site. It is a bramble covered bank with no visible masonry.

Dimensions & Materials This is a low bank about 1 metre high on its south side, running from a field stile to the boundary wall of the priory site for a length of 27 metres. West of the stile a low bank runs alongside a track westwards without any visible sign of the wall. The wall is entirely covered with vegetation and masonry is not visible. However it is solid and flints can be reached by pushing a rod through the dense bramble. Vegetation Dense bramble covers the section and west of the stile it is a hedge topped bank.

65. South (field) side looking east 66. North (track) side looking east to priory

boundary wall Animal damage There is some evidence of rabbits, but they do not appear to be causing a problem. General condition It is impossible to asses the condition of the wall without removing vegetation on the south side. Otherwise it appears to be an earth covered bank. Work required

Consideration might be given to the removal of vegetation to expose the wall. Its true length could only be ascertained by excavation. An option would be to leave it alone.

36

VEGETATION MANAGEMENT "How best to conserve ruined monuments? What role does vegetation play in ruined sites? These questions have been debated for many years, and remain of great importance today. The history of presentation of ruined sites in England illustrates changing views on the role of vegetation, encompassing both ‘romantic ruins’ and ‘stable but sterile monument viewpoints’. Current views on presentation of ruins suggest that vegetation can enhance a site, as long as it does not cause damage nor conceal important elements."1 The control and management of vegetation has implications beyond the simple consideration of the condition of the precinct wall. The character of this part of the Conservation Area owes much to the trees and bushes which provide a ‘green backcloth’ and cover above sunken lanes. Indeed the Castle Acre Conservation Area Character Appraisal2 describes South Acre Road as “…a sunken, rural road characterised by grass banks, hedges and trees with branches which arch over confining views”. Priory Road is described as having “…its rural character emphasised by the absence of footpaths, raised verge, hedges and trees. A view opens out over the grounds of the Priory to the opposite valley side.” So any removal of vegetation to repair the precinct wall remains will have a serious impact on the character of the Conservation Area. Not only are there aesthetic considerations, there is also the need to protect wildlife interests. The mix of meadow pasture, tree and hedgerow banks and stands of mature ivy, together with the wildlife corridor provided by the River Nar, creates an important natural habitat. A decision will have to be taken on the extent of vegetation management given these implications. Public support for vegetation removal will only be forthcoming if the issues are properly explained and understood. There are sections of wall which pose public safety problems too and this needs to be explained fully.

1 ‘Soft capping historic walls: A better way of conserving ruins’ Lee Z, Viles HA & Wood CH 2009 English Heritage Research Project Report p.6 2 ‘Castle Acre Conservation Area Character Appraisal’ Borough Council of King’s Lynn & West Norfolk 1971, revised 2009 pp 7-8

37

An overall aim or vision could involve the eventual removal of vegetation from all standing masonry and the earth capping of banks where masonry is low or not visible. (These stretches of wall and bank have been identified in the Condition Survey above). Within this overall aim, certain guidelines should apply:

Ferns, mosses and lichens should be retained wherever possible. Small flowering plants and grasses should be retained wherever possible and larger

plants be removed only where woody roots are penetrating mortar. Root stumps which cannot be removed without damage should be painted with a glyphosphate- based herbicide3. (Spraying is not recommended as it destroys surrounding flora).

Trees, saplings, brambles, ivy and woody plants should be removed in a phased programme where affecting masonry. As it is difficult to remove roots without causing further damage, they should be cut off as flush as possible to the masonry and the cut surface painted (not sprayed) with a glyphosphate-based herbicide. Once the root has died, it may be possible to remove it or if this is likely to cause damage, it can be left to rot away and the masonry subsequently consolidated as necessary.

Well established stands of ivy, bramble and bushes may support breeding birds or roosting bats and cutting back should not be undertaken during the spring or summer (February to September).

Mitigation may be possible if areas can be found for tree planting, between the precinct wall and the inner fence, without harming archaeological remains. This could be used to partly compensate for tree loss.

RABBIT CONTROL The precinct walls enclose sizeable series of rabbit warrens and their burrows have undermined the wall in places, exposing and excavating below foundations. The damage caused is detailed in the Condition Survey above, but certain sections of wall are affected more than others. The two sections along Priory Road (section 3 and especially section 2) are the worst affected, but there is damage elsewhere (sections 5 and 6 and section 1 where rabbits are burrowing beneath the corner of the gatehouse). Not only do the burrows damage the wall, they are also often concealed amongst nettles and other plants, creating a trip hazard and providing a terrain which will cause difficulty in providing level ground to access standing masonry to be repaired. A programme of control is recommended, starting with sections 2 and 3.

3 NB If herbicides are to be used it is important to be aware of and adhere to the legislation requiring operatives to hold the necessary certification for their use and to strictly adhere to manufacturers’ instructions and product information in the interests of health and safety.

38

REPAIR PRINCIPLES Lime Past repairs have included the use of cement mortars to cap the wall and to consolidate the core material where exposed. The effectiveness of this approach has been compromised by the waterproof nature and inflexibility of cement. Its further use is not recommended. Lime mortars are permeable and flexible. They have been used to build the wall originally and to bind the core material. It is recommended that lime be used for all future repairs. Flintwork The flintwork comprises a core of flint and occasionally chalk fragments set in a lime mortar matrix. The wall faces are of random sized flints which are invariably laid in courses with narrow joints between flints. The result is sections of masonry with clear horizontal rows of flints. It is essential that repairs precisely match this detail, using wherever possible salvaged flints and all set in a lime mortar. Consolidation of exposed foundations Where masonry is missing at the base of the precinct wall (often due to rabbit burrows) it will be necessary to provide a suitable ‘soft’ remedial foundation. Well compacted crushed chalk should be provided beneath the wall to a depth of at least 250mm. The crushed chalk should be well graded in sizes from 19mm down to 3mm and compacted by hand ramming using a hardwood ram. The thickness of the foundation will need to be determined for each section underpinned in this way. Care must be exercised when excavating each small section of remedial work to ensure continuity is provided with any existing foundation. Buttresses In the Condition Survey above, consideration of buttressing is suggested for two areas of wall in section 8; the top-heavy masonry at the ford gap, behind the bench and the leaning masonry to the west of the gap. In the case of the former, it is important to ensure that further erosion of the exposed core material below the cap is arrested. Structural engineering advice is recommended and if buttressing is required, red bricks set in a lime mortar are suggested as suitable materials. Soft capping The use of earth or turf is suggested for banks and sections of wall which are low. The English Heritage Research Project Report ‘Soft capping historic walls: A better way of conserving ruins’ edited by Lee, Viles & Wood (2009) provides a useful discussion on the topic and gives practical advice on how to do it.

39

40

Craftsmanship and supervision It is important that the nature and extent of the work, including mortar mixes to be used, are specified clearly. This will enable fair tendering and will give the contractor a clear idea of what is expected. The full extent of repair work will not be fully apparent until areas of vegetation have been removed. It is of even greater importance that the workmanship of flintwork repair is carried out well and there is proper supervision. Supervision of work would include the approval of precise areas of flintwork repair, the approval of mortar material, the approval of tools used and the approval of a test area of consolidated flintwork, which should be retained throughout the job for comparison. Maintenance It is important to ensure that as sections of wall are repaired and cleared of vegetation and banks are capped, a programmed of maintenance is agreed to prevent future deterioration. This need not be onerous and might simply require an annual condition inspection and cull of fresh ivy and other growth. The condition of the precinct wall will rapidly deteriorate if no maintenance programme is put in place.

RECORDING If it is agreed to remove vegetation, a full photographic record of the exposed sections of standing masonry should be made. This Preliminary Condition Report is limited by the inability to view the sections of wall properly where covered by ivy, bramble and other plants. So when cleared, the opportunity should be taken to provide a more detailed record before repair work begins.

PHASING & PUBLIC SAFETY Generally, the condition of the wall poses few public safety issues. However, sections 5, 6 and 8 do pose problems. Along South Acre Road, flintwork at a high level above the road is affected by lateral tree and bush roots and near the ford, where public activity is at its highest, there are two sections of standing masonry with stability problems. Additionally there are areas of rabbit burrowing which could threaten stability (notably in sections 2 and 3). Accordingly, it is suggested that the following phased programme of work be adopted:

1. Rabbit control 2. Consolidation of the wall following vegetation removal in sections 5

and 6 3. Stabilisation of masonry in section 8 4. Repairs to sections 2 and 3, including soft remedial foundation work. 5. Repairs to section 1.