Restoring The Corona On Minchinhampton Church

This is a Report on the talk given by Richard Bossons at our meeting on March 25th 2010. Report by Nick Miles.

Holy Trinity Church MinchinhamptonRichard Bossons treated members and guests to a very well-presented and informative talk on the restoration and conservation work carried out to the stone corona at Holy Trinity Church, Minchinhampton in 2005.

Parts of the church’s broach tower date back to the fourteenth century but its current form and appearance, which incorporates a truncated, octagonal spire with stone corona, battlements and finials, apparently dates from 1563. As with most buildings, running repairs were carried out as and when required (and generally left far too late).

It would appear that the Victorians were responsible for some well-intentioned strengthening repair works in the form of wrought-iron tie-bars and pins. Unfortunately, such materials have proved particularly unsuitable, especially where their location is subject to moisture (iron rusts on contact with moisture and oxygen and massive expansion forces are set up which essentially blow the surrounding stone apart).

Richard BossonsRichard Bossons (pictured left) was mason-in-charge of the project and was working on behalf of Miserden-based stonemasonry company Centreline Architectural Sculpture, which was awarded the repair contract.The corona (which means halo or circular band) consists of a taller central pinnacle surrounded by four shorter satellite pinnacles. The pinnacles are decorated with crockets, which were probably originally in the form of buds, flowers or leaves but have deteriorated over time, leaving minimal detailing at best. Four cranked sections of stone merlons and embrasures (the up and down bits!), link each of the satellite pinnacles around the perimeter of the corona (these are sometimes referred to as pierced battlements).

Richard described and illustrated (with photographs) the methodology in taking down the original and badly corroded stonework; it was critical to ensure that dismantling was carried out in the correct order so that loads continued to be distributed safely.

Most of the cutting and working of the stone was carried out at the Miserden yard and brought to site. The working and carving of stone is carried out by ‘bankers’ – not the infamous bankers we all love and trust, but highly trained artisans who should command our utmost admiration.

New limestone was sourced from Burgundy in France, the decision greatly influenced by its successful use on the recent and on-going work at Gloucester Cathedral. The original stone would most probably have been the excellent-quality Minchinhampton weatherstone, but this is no longer available. Approximately 16 tonnes of imported stone was used in the restoration.

Richard Bossons(this picture shows the central stone-vaulted roof within the walls of the corona which required extensive repair and strengthening work)

The initial estimate for replacement of damaged/defective stone was based on around 30 per cent. Unfortunately, however, once dismantling had taken place it was evident a far higher percentage replacement would be necessary. An accepted conservation principle is that the absolute minimum number of stones should be replaced, so as to maintain authenticity.

However, in some cases, especially where high access costs (i.e. scaffolding costs) are involved, it is accepted that a more pragmatic approach can be taken to ensure that the area does not have to be revisited for a far longer period than might otherwise be the case (work to cathedral or church towers is often carried out in 100 to 150-year cycles and it is with this in mind that decisions will need to be adjudged).

Richard Bossons(this picture shows the new work including: merlons, embrasures, crocketed pinnacles, lead work and other stonework)

Another key element of the work was to remove the embedded (and in some cases the exposed) ironwork. This was replaced with stainless steel where required. The most notable piece of stainless steel introduced was the central dowel, which runs down the centre of the central pinnacle; it is nearly 4m in length, threaded and 40mm in diameter.

New excellent-quality leadwork was introduced to weatherproof the roof of the central vault. Unfortunately, this is completely out of view from ground level, but may well be worth a visit on Google Earth.

The top of the central pinnacle now also houses a gilded weathercock, very generously donated by a local resident and businessman.

Richard concluded his talk by discussing how grateful he was to have worked on such an unusual project and answering a series of audience-led questions.

A thoroughly enlightening and informative presentation. .

Richard Bossons now works as a freelance architectural stone carver and mason from his workshop near Nailsworth and can be contacted by email at: richard.carving AT virgin.net and will have a website up and running very shortly.

Centreline are at Miserden and can be contacted at: www.centrelinestone.co.uk/centrelinestone.

Nick Miles – Stroud Civic Society, March 2010


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