Full Report for Listed Buildings

Summary Description of a Listed Buildings

Reference Number
Building Number
Date of Designation
Date of Amendment
Name of Property
Fonmon Castle  


Unitary Authority
Vale of Glamorgan  
Street Side
On the north side of the B4265 but approached via a drive from Fonmon village.  


Broad Class

There is speculation that a timber castle was erected on this easily defensible site soon after the Norman Conquest of South Wales, and that the first stone building was then added in about 1200. This would have adjoined or even been within the timber enclosure, but physical evidence, apart from the changes in level in the gardens and outworks - except for the so-called Watchtower (qv) - is no longer apparent. It is perhaps significant that the first surviving stone build is well away from the edge of the ravine. This is the section on the left of the entrance court running east-west and containing the Drawing Room in what was the first floor hall of the castle. This section has the thickest walls of the present building. Since the first build is relatively small, approx. 8m x 13m, it must be imagined that it was only a part of what continued in use until more of the stone castle was built. This was the east curtain which extended the existing range to the edge of the precipice and then turned the south-east corner to include the south range. The rooms within the east curtain, now the Stairhall, are believed to have been created by Colonel Jones (see below) in the 1660s with both the west wall and the roof dating from then, but it would probably have had some sort of building against it previously. Curiously the thickest section of these walls are along the ravine edge on the east side where attack might be considered least likely so the more vulnerable south and west approaches to the castle must have continued to be defended in some further way not now apparent. These additions, with both square and rounded towers, must be from fairly early in the C13, for the more vulnerable square corner tower type quickly fell from favour. (Rochester Castle for instance had its corner tower rebuilt in circular form after being undermined in the civil war of 1216; while Grosmont and Skenfrith Castles in Monmouthshire were given all semi-circular towers in about 1230.) All this was probably built by the St. John family, who were certainly owners later in the Middle Ages and continued as such until 1656. The open quadrangular form of the C13 castle with apartments set against a curtain wall would strongly suggest that it was intended to complete the quadrangle, but this appears never to have happened, and the next major addition seems to have been a short north wing built in the C16 over a characteristic barrel-vaulted semi-basement. The castle seems to have gone undamaged through the Civil War with the St. John family supporting Parliament, but they later fell on bad times financially and in 1656 sold the whole of their Glamorgan estate to Colonel Philip Jones whose successors still own it today. The Colonel is said to have been responsible for the addition of the double depth wing on the north side of the castle and also the rooms of the east range, but some of the internal decoration may date from after his death in 1674 and be attributable to Oliver Jones who owned the castle 1678-85. The next major additions, giving it most of its present internal character, was the work of Robert Jones III, great-grandson of Oliver Jones. He married Jane Seys of Boverton in 1762 and began the castle improvements by employing Thomas Paty of Bristol to undertake them. This firm had done similar makeovers to houses such as the C16 Stoke Park north of Bristol in 1760-4, and they supplied the overall battlements and render to enhance the castle look while at the same time putting in a regular display of sash windows to improve light levels internally, and remodelled the interior for comfort and elegance. This involved breaking through walls to increase the size of rooms, thus forming the Stairhall and the Drawing Room, and making further improvements to the service end following what had already been achieved in the late C17. The C19 saw the estate in decline and little was done to the castle except for the addition of the entrance porch and the extension to the south wing in the period between 1840 and 1878; the extension appears to be shown on the Tithe Map of 1841. There is, however, the possibility that alterations in the C19 may have been more considerable than imagined, with mid C18 pastiche on the staircase and in the Dining Room for example, but this is uncertain. The castle passed by marriage to Sir Seymour Boothby in 1917 and his grandson still lives there.  

The castle is constructed of local limestone and blue lias rubble as can be seen internally, one arched doorway internally appears to be Sutton stone; but the walls are completely covered in unpainted grey render which effectively disguises all building stages and changes. The roofs are of mixed slates, presumably Welsh, but some are very brown, with lead gutters and dressings. The building is in castle form, of two and three storeys and castellated almost throughout. The walls are largely uniform in height apart from the south-east corner tower which forms a look-out. The main entrance is on the west, set between projecting wings, a mid/late C19 porch coming forward from the hall with a service entrance in the wing on the left, which also has two 6 over 6 pane sash windows to the left of it, and two sash windows on each floor above, arranged fairly randomly. The service door is a panelled late C18 one. The main entrance porch has panelled double doors. It has a 6 over 6 pane sash to the right of it and in the wall above, behind and to the left are two large 12 over 12 sashes which light the Stairhall, with a third one to the right. To the right again the wall of the south wing is blind and the two bay extension, which has a doorway, cannot be recognised. On the south-west corner of the castle the end of the wing is blind and next comes the south elevation. This has a two storey 5-bay front with an additional bay formed by the projecting south-east corner tower. From the left the first two bays are the early/mid C19 addition (it is seemingly shown on the 1841 tithe map) but all windows are 6 over 6 pane sashes, except for the right hand ground floor one which has late C20 French doors below the fixed top sash. This doorway was converted from a window in the late C20 but it is said to have been the main entrance doorway during the period from the 1760s alterations probably until the C19 alterations. There is a considerable breadth of blank walling between the upper sashes and the castellated parapet, one external indication that this is indeed a development of a real castle. The corner tower, which is square, only has a window at mezzanine level on the south wall, this is a 2-light Victorian one in Bath stone with Caernarvon heads to the lights. Arrow slits in the wall above. There is a small doorway in the return angle on the left and this was presumably the entrance on this side of the castle prior to the 1760s alterations. The east wall faces over the ravine and again underlines the reality of its castle origins. First comes the blind wall of the south-east tower, then a half-round tower which has a port-hole window (possibly a gun-loop) below and two arch-headed casements above. Then a length of curtain wall where the details are much obscured by creeper, but there are two sash windows on the ground floor which light the Stairhall. Then comes a projecting piece with a probably C20 glazed door below and a canted oriel above, which is the east window to the Drawing Room. This has three 6 over 6 sashes arranged as a Venetian window with an arched and keyed centre. A stair tower comes next with small windows at four levels and then the wall sets back with a further five bays of windows, the first being a randomly arranged ground floor sash with a small arched window above and a large arched sash above that. The upper two of these are the windows to the late C17 staircase compartment. Then follow three storeys of regularly spaced sash windows over a gradually heightening basement, this is the late C17 double-depth extension. The north side of this wing fronts the sunken service court. The ground floor has various doors and the small projecting wing houses the estate brewery. In the wall above are four different sized windows at differing heights. The west elevation begins with a regular four bays of sash windows as on the east side, but there are only two storeys of them above the mostly sunk service rooms; there are also three windows at basement level. The top two floors have 9 over 6 sashes and are evidently in late C17 openings intended for mullion-and-transom casements. Next comes a bay with a lower parapet line, though still castellated, and this has a 9 over 6 sash above and French doors under a 6 pane fixed sash below. Finally comes the projecting tower which is the west end of the original build. This has only a stone framed Venetian window, the Drawing Room west window. The glazing for this has been altered later to include central French doors onto the raised terrace. To the right of this is the entrance court at the lower level once again. The roofs are almost entirely hidden behind the castellated parapets, as are the chimneys, no doubt deliberately so as a part of the late C18 'castle' look. The roofs are arranged with a ridge for the south wing, another for the east curtain, an east-west ridge across the building for the original build and parallel ridges for the C17 north wing running north-south, of which the west one is slightly smaller.  

The interior of the castle has seen many changes and it is now difficult to sort out the uses the rooms have had in the past and the dates when the changes have been made. The principal character is now of the mid-C18, modified, but in the same style, perhaps in the mid/late C19. It has been assumed that all the C19 alterations are of the same date, in fact that of the porch and therefore c1840-78, though this may not be the case. The castle is currently entered through the Victorian porch directly onto the Stairhall via what previously may have been a window. RCAHMW say, however, that this was Colonel Jones main entrance in the 1660s (but see below). This room is clearly an amalgamation of two rooms on each floor but this seems to have been achieved at two periods, firstly when the stair was inserted into the southern half of the room and secondly when the two rooms to the north were included in it. This second change must have happened either in the late C18 or is partly a late C18 pastiche done in the mid/late C19, perhaps when the hall was made into the main entrance (if it was at that time). These changes can be explained in several ways, but the main puzzle is the bottom of the staircase which would need originally to have been turned at right angles at the bottom to fit within the south room. In the 1760s the main entrance to the castle appears to have been through what is now a French door on the south elevation. This door is late C20 and was previously a sash window like the others so must have been changed when the main entrance was moved to the west courtyard. This entrance would appear minor for so important a house but it is known to have had the entrance drive aligned on it . There is also evidence of an entrance directly into the tower on the right in a sally-port position and this reaches the Stairhall from behind the staircase. The mid C18 doorway entered a lobby, now included in the main south room, but ceiled separately and intended to be an entrance hall. The rest of the south room, no doubt once entered by double doors, seems likely to have been the State Dining Room, despite being so far from the kitchen. It is the only room that could take advantage of the late afternoon sun and its position beside the front door would also have been convenient in use. After the Victorian alterations it became the Drawing Room and the room added beyond, through the panelled double doors (probably these were previously the doors from the entrance hall), was the Smoking Room. The main room has a simple late C18 plaster cornice and fireplace. There are pilasters at the join of the rooms and the former entrance hall has a panelled dado, additional Rococo decoration to the ceiling and a grand doorcase as entry to the Stairhall beyond. The alterations in the 1760s were undertaken by Thomas Paty of Bristol and the plasterer Thomas Stocking; the Rococo work at the castle is very characteristic of him. The use and decoration of these next rooms in the period 1680-1760 appears to be largely unknown and yet this is vital to an understanding of the way the house worked and of the ideas used by Paty in the alterations. There must surely have been a staircase at this end of the house during this period, but was it in the same position as the current one? The Stairhall contains an apparently late C18 staircase with two turned balusters per step, cut string with scrolled tread ends, a curtail and a moulded pine handrail. It climbs in two slightly awkward flights past a landing with an 8-panel door which gives entry to the south-east tower with its different floor levels. Similar door on the upper landing into the main south range. The stair enclosure has a Rococo ceiling and windows in the upper and lower west wall. The north end of the hall has a late C17 bolection moulded fireplace on the ground floor but there does not seem to have been a matching one in the wall above. The upper part of the room is entered through a flat headed break in the wall, framed by pilasters and the upper landing is carried on a cantilevered balcony with turned balusters and handrail as before. All this suggests that the northern end of the ground floor with the windows flanking the fireplace was the late C17 Dining Room and, after 1760, but before the present Stairhall was formed, would have been the Breakfast Room (it faces east) or the family Dining Room (it's much closer to the kitchen). The upper part of the room would have been a small Withdrawing Room, but it was apparently unheated so it must have been just an anteroom. The west facing windows are of C17 dimensions. The ceiling with cornice as before and central Rococo decoration, is higher than that over the stair. Having progressed from dinner up the stairs and through the first apartment the largest and finest room is now reached. This is the Grand Drawing Room and Library running from east to west across the building and being lit by a Venetian window at either end, a stone one to the west and a timber oriel to the east. This room is mostly within the first floor hall of the first build tower but no evidence remains of what it might have been like before the 1760s. The room is divided into three sections with the largest in the centre. This is framed by extremely flattened segmental arches at either end, the east one being a break through the c1200 wall of the first build, the west one an invention of Paty's as a balancing device. The soffits of these arches are coffered with plaster flowers and with bearded heads as keyblocks; while the arches are supported on panelled pilasters. The main ceiling has trophies of the chase in the spandrels and arabesques and wreaths on the flat, with a central Apollo head in a sunburst. The gilt chimneypiece is copied from a plate in Thomas Johnson's 'Collection of Designs' published in 1758. Payments for work to this room were made to both Paty and Stocking in 1766-7. The west part of the room is further lit by two windows overlooking the entrance court on the south. The south-west door from this room goes through to a private Library or Study, while the main door on the north side is onto the family stair and rooms in the late C17 north wing. This staircase rises only from the Drawing Room floor to the upper bedrooms. It is a late C18 open-well stair inserted into an existing space and in details the same as the main stair. Several of the larger rooms in the north wing have full height panelling and bolection moulded fireplaces characteristic of the late C17. To return to the ground floor the service end of the house is entered at the north end of the Stairhall. The basement of the original build contains the Estate Office and a windowless room with a stone staircase rising through the wall into the C13 addition. The north wing has a spine corridor with the first room on the left a barrel-vaulted C16 'Cellar' with a large fireplace. This is likely to have been the main Kitchen in the C16 and C17 before the new Kitchen was built in the 1660s. This is beyond on the east side and contains good fittings of the early C18 (dresser) and Victorian period (cooking ranges). At the head of the stair is a chamfered pointed arch of Sutton stone which could be C16, but the stair itself is believed to be C19. It is cut very clumsily through the medieval walls and has a rather uncertain marriage with the bedroom stair as if it is an afterthought. The stair continues as a mural stair up into the C13 tower while the arch leads to the bottom of the family stair described above. The mural stair is one of the few medieval castle features still visible internally. There is another stair in the south-east tower, there are several rooms at the top of the two towers with circular corbelled roofs (six in all), and two garderobes are visible with the probability of more. The first floor room in the south-east tower shows signs of having been worked on in the Victorian period; it has a 2-light window and walls dressed with blue lias; this may have been an unfinished intention as a 'medieval' boudoir. The visible timber roofs are all C17 and of the principal rafter type, but with many repairs and alterations. The developmental history of this interior remains unclear. Questions still unanswered concern the C17 staircase, the former nature of the rooms making up the present Stairhall, the uses of the rooms at different periods and the particularly vexed question of the main access to the house at different times, especially from 1660-1760. There is also the very confusing question of how much of the apparently C18 decoration and alterations may actually date to the C19.  

Reason for designation
Included and highly graded as a very unusual example of a medieval castle converted into a high quality late C18 country house with important Rococo decoration.  

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