Restoring Clitheroe Pinnacle
In 1834 what has become known as the Great Fire swept through the Houses of Parliament, destroying much of the old building and leaving only the Westminster Hall intact. The competition to design the replacement building was won by the already well known architect, Charles Barry. Barry enlisted the help of AWN Pugin with both the competition drawings and the subsequent construction plans and designs.
The selection of the most suitable stone for the new building was subject to a long process by a small committee. It eventually settled on magnesian limestone from a quarry at North Anston, now in South Yorkshire. This was an unusual choice. While some notable buildings, including York Minster and both the Manchester Athenaeum, are constructed of it, it is not a popular building material.
The stone was pulled on horse-drawn sledges to the Chesterfield Canal, transferred to canal barges, towed up to a tributary of the Humber, further transferred to sea-going barges, and taken up to the Humber, down the east coast to the Thames and up to Westminster. Sufficient stone was quarried and moved to complete the majority of the work by 1860.
An unfortunate consequence of the need for very large quantities of stone within a relatively short period was that some of the material was of poor quality. This became apparent when in 1904 the first of a series of major repair programmes had to be undertaken. The national archives contain some wonderful watercolours showing the extent of the deterioration in some of the stonework.
Most of the stonework was intact (even today at least half of the external stonework is original), but some had succumbed to the atrocious atmospheric pollution. The assumption is that these sections were the poorer quality stone.
In the 1930s, the second major repair phase resulted in the replacement of seven roof-level pinnacles, one of which made its way to Clitheroe, Lancashire. While the details of the necessary negotiations are unknown, the then MP for Clitheroe, Sir William Brass, ‘acquired’ the six-metre-high pinnacle, had it shipped up to Clitheroe and rebuilt in a specially made rose garden in the grounds of Clitheroe Castle. Brass presented it to the town as a commemoration of the coronation of George VI in 1937. It has remained there ever since, receiving some repairs over the years but largely being ignored until recently, when the possibility arose of it having to be dismantled due to concerns over public safety.
In 2013 a member of Clitheroe Civic Society raised concerns for the future of the pinnacle. This set in motion a train of events that saw the society instigate investigative work, successfully apply for Heritage Lottery Funding, and run a project to repair and consolidate the structure to make it fit for at least another generation. IWA Architects of Clitheroe was appointed.
The structure is listed Grade II and the local authority is Ribble Valley Borough Council (RVBC). Although the project was instigated and carried out by Clitheroe Civic Society (CCS), the pinnacle is owned by RVBC, which was necessarily heavily involved with the project.
Various issues were apparent from the outset: deterioration of the stone itself, water ingress due to both stone and joint defects, and damage caused by oxidation of ferrous elements.
Magnesian limestone stone is relatively soft and can weather to a somewhat alarming extent. Earlier repairs to the pinnacle had been made using a stone that is very similar in appearance to the original but which has eroded to a much smaller extent: the newer stone now stands proud of the older. There is no reason to assume that the surfaces were not made flush at the time of the repair.
The philosophy underpinning the approach to the work was one of repair and consolidation, rather than restoration. However, it was evident that some sections of stone would need to be replaced to make the structure safe. The issue of where to source this material was problematic as the original quarry closed some years ago. Consultation with parties involved in the current Palace of Westminster repairs revealed that they had been using Clipsham stone. This is an oolitic limestone rather than a particulate stone. Although the colours of the two rocks are similar, their appearance is not, Clipsham stone having a shinier surface.
Following advice from Palace of Westminster sources, we used magnesian limestone from Jackdaw Quarry, Tadcaster. This is from the same band of rock as Anston, although somewhat further north. Its colour is similar to the original but its texture much smoother. However, it is expected that it will weather in a similar way to the original and eventually provide a better match.
One factor that might have been the cause of some of the serious deterioration concerns the natural bedding of the stone. The selection of some poorer-quality material might be responsible for the opening up of some quite deep cracks in our pinnacle. Some joints had also opened up on the plinth, probably due to a small amount of subsidence and subsequent water ingress. However, as these joints were relatively free draining, no serious damage had been caused. The main area in which water penetration had caused serious damage was the top-most section, where oxidation was a problem.
As with the current Palace of Westminster, the original design of the pinnacle included a metal rod on the top with a weather vane. This consisted of a non-ferrous exposed section attached to a ferrous enclosed portion. In our pinnacle the non-ferrous section had been sawn off level with the top of the stonework and a rough cement cap added. This had deteriorated over the years and allowed water to enter and filter down to the ferrous rod. This had oxidised severely, badly damaging the top section of stonework.
It was expected that most of the joints would incorporate ferrous cramps as some small sections of metal were visible. A cover-meter survey did not reveal any evidence of internal metal elements. When the pinnacle was dismantled it was discovered that virtually all the joints were secured using slate pegs, with only a small number of ferrous cramps being found joining the larger slab sections. The small pieces of exposed metal appeared to be the remains of earlier repairs that had failed.
Some very strange constructional methods were used in the stonework. While some of these could be explained as being the most appropriate way to secure various elements, others were completely baffling. The most likely explanation was that a mistake had been made during the initial rough shaping of some sections and, due to the shortage of stone, it was decided to correct the mistake rather than discard and replace the whole section. Whatever the reason, the contractors had never seen anything similar.
As mentioned above, the expected ferrous pins were not found, but a potentially more challenging issue was encountered. Either during the reconstruction of the pinnacle in 1937, or as part of later major repairs, an extremely strong mortar had been used in combination with a different, but equally strong, filler. This, being stronger than the stone, caused some damage during the dismantling process. It was decided that the safest approach was to cut through the mortar, leave it attached to the stone where necessary, and incorporate it into the rebuilt structure.
The dismantled parts were cleaned up on site, apart from the heavily fractured top section, which was taken to the contractor’s workshop to be pinned and bonded. A test panel using three slightly different coloured mortar mixes was prepared and the most suitable chosen.
The intention was to replace as little stone as possible. A new central core in the base section was added to replace earlier cementitious fill and one section of one of the mullions was replaced. Other than this, only small pieces were required to fill gaps that had developed over the years. From a conservation point of view this was very pleasing, as almost all of the original structure was able to be retained. From the Civic Society’s point of view in promoting the project, it was necessary to explain where the Heritage Lottery Funding money had been spent, as the resulting structure appeared to be almost identical to the previous one.
Because the pinnacle had been in the town so long and was in a prominent position in the castle grounds, it held a special place in the hearts of many residents. We were regaled with many stories of the role the site played in school visits, teenage gatherings and courtships, and a number of old photographs were produced. Where possible these were added to the website that was set up to promote and document the project.
The backing and involvement of the local community was vital, not only to fulfil Heritage Lottery Fund criteria but to make it worth carrying out in the first place. The civic society would not have pursued the project if the pinnacle had been of no value to the townspeople. A petition and public meeting had shown that there was a great deal of interest and desire to see the project go ahead.
This interest was evidenced through the involvement of one particular local primary school. Coursework, art work, visits and talks were enthusiastically undertaken by pupils, and their work was displayed in town-centre shops. Site visits were organised as part of Heritage Open Days, enabling 60 visitors to see the dismantled pinnacle and have the work explained by the contractor. An open 3D model competition for young people was well supported and the results were displayed in three high-profile locations in the town centre.
Two fundraising events were organised. One was an evening garden party in the grounds of Downham Hall, the home of Lord Clitheroe, who supported the project. The other was a concert of music from a local artist, choir and ukulele orchestra which was very well attended.
The project manager provided weekly articles for the local newspaper, and bulletin boards were placed in the town library and Clitheroe Castle Museum. The website was kept populated with photographs and short presentations describing various aspects of the work and has become a major information source. This was coupled with a project book describing the wider aspects of the pinnacle and project, with chapters on the history of the Great Fire; the rebuilding of the Palace of Westminster; Sir William Brass MP, who brought the pinnacle to Clitheroe; the project repair work; and the fundraising and awareness-raising work carried out.
Related articles on Designing Buildings Wiki
- Cement mortar.
- Community engagement in conservation.
- Conservation in Chester.
- Defects in stonework.
- Houses of Parliament.
- IHBC articles.
- Lime mortar.
- Listed building.
- Principles of conservation.
- Restoring Charles Drake's concrete house.
- Restoring Kew’s Temperate House
- Restoring Singapore shophouses
- Scheduled monument consent.
- The Institute of Historic Building Conservation.
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