Craftsmen restore country house to former glory: Sculptors use delicate skills to recreate rococo ceiling destroyed by fire. Oliver Gillie reports

THE piano nobile at Prior Park in Avon was once one of the finest sets of rooms in one of England's most splendid mansions. Now it is a mass of scaffolding. Corinthian pillars stand among steel poles and a builder's ladder provides the only access to the gallery from where, in the 18th century, Alexander Pope used to admire the view of Bath in the valley below.

A fire at Prior Park in 1991 destroyed most of the interior decoration and now a team of craftsmen are recreating panels of freehand plasterwork which decorated the ceiling of the piano nobile. At the same time, the central portion of the mansion, which is used as a Catholic secondary school, is being rebuilt while schoolwork continues in the stables and servants' quarters.

Temporary planking has been installed 12ft above the original floor of the gallery, making a strange room with curved walls in the cove just beneath the ceiling. The walls of the cove were originally hung with plaster panels decorated in the rococo style, with arabesques of fruit and leaves, and themes of gardening, hunting, music and war. Many of the panels were broken up in the fire and are now being reconstructed like large jigsaw puzzles.

The panels are believed to have been made originally for Hunstrete House, near Marksbury, Avon, and bought second-hand by Bishop Baines, who founded the Catholic school on the site.

The plasterwork had excited little interest until it was destroyed by the fire of 1991, so it was never properly photographed or recorded. Most of it was modelled freehand, although a few pre-cast elements were included. Now the plasterwork is being reconstructed by St Blaise, a company specialising in restoration, and the architects Ferguson Mann, from fragments and from the few photographs that have been found.

The 18th-century craftsmen who made the original panels used stucco made from lime mortar mixed with marble dust, a small amount of gypsum and animal glue. This produces a fine putty, which will remain soft for several hours in a large lump but sets within half an hour when modelled into smaller shapes.

Some panels were totally destroyed and must be entirely remodelled. Caspar Taylor and John Toffee, both sculptors, are producing the first new panel for approval.

'We have about half an hour to model an individual piece of encrustation before the stucco dries,' Mr Taylor said. 'It is completely different from modelling with clay. A clay model can be added to, or cut away, but stucco must be built up slowly. We can't pare it down if it is too large.'

This technique, imposed by the material, gives freehand decorative stucco work its special quality. The flowers, fruits and leaves are never exactly the same and panels, which seem at first to be symmetrical are, in fact, not exactly true.

Ian Constantinides, a director of St Blaise, said: 'Two modellers working from the same reference will produce work which differs in subtle ways. We have to maintain the element of freedom to produce spontaneous work but at the same time we are trying to produce exact copies.

'It is a difficult task. But this freehand work has so much more life in it than the cast work which became increasingly common during the 19th century.'

Some panels which were almost totally destroyed will have to be rebuilt using inspired guesswork. The St Blaise team hope to reconstruct these panels by copying from similar rococo plasterwork at Harewood House and Burton Constable House in Yorkshire. The work there is believed to be that of a craftsman called William Collins who is also thought to have been responsible for the work at Prior Park, or at least used the same patternbooks.

Finally the the plaster ground will be painted lilac, green, or a straw yellow, the original colours discovered by paint analysis. So the modelled stucco will appear as encrustations against the coloured ground.

'We are using skills which had been almost forgotten. During the 1950s and 1960s, restorations were done using modern techniques and by casting the decorative elements. The results were generally ghastly.

'Now there is an academic interest in getting it absolutely right and to do that we have gone back to using the original methods,' Mr Constantinides said.

(Photograph omitted)