St Nicholas at Wade Church on the Isle of Thanet, dating back to the 12th century and containing exceptionally high quality medieval carvings echoing decorations in Canterbury Cathedral, represented some interesting challenges to stone and conservation specialists PAYE when they were called in to repair the south-western tower.

The tower\'s lower section dates from about 1310, but the upper section on which PAYE\'s restoration experts worked was a slightly later addition thought to have been built as a navigation aid when Thanet really was an island.

This top section has a castellated wall constructed of heavily mortared flint pebbles, originally collected from the nearby beach. The wall is filled with rubble and capped with Kent ragstone copings.

Despite late Victorian attempts at rebuilding the wall, the upper two thirds of the 23m high tower had suffered from hundreds of years of coastal exposure. There were disintegrating copings, missing embrasure stones and some castillations starting to lean - in fact, some hefty lumps of masonry had already fallen to the ground.

Before repairs could start the complex matrix of interlocking external stones had to be recorded and as the tower top was dismantled all the materials, including the original rubble fill, were stored for re-use.

Copings, embrasures and merlon stones that needed replacing were prepared off site. Once hoisted to the top of the tower all the new parts of the castellation were hand crafted to match the originals exactly.

The medieval mortar that had held together the original wall was laboratory tested

and exactly replicated, even down to oyster shell fragments sourced from the nearby coastline, for rebuilding the flint and ragstone wall.