With huge eyes, a broad nose and wide lips, it's an unforgettable face - and one that probably hasn't been seen for hundreds of years. A beautifully-crafted carved stone head, thought to date back to the 11th century, has been discovered during work at a medieval church on the Norfolk coast.

Historians, conservationists and volunteers are half way through a two-year project to conserve and consolidate Old St Margaret's Church in Hopton-on-Sea, between Great Yarmouth and Lowestoft. The grade II* listed structure has been a ruin since it burned down in 1865.

Yesterday, during a routine visit to the top of the church's 50ft tower to inspect progress, project director Darren Barker spotted something - something which looked like the top of the head.

The large, carved face was carefully extricated by Great Yarmouth Preservation Trust conservator Frederique Van Till.

Based on its Romanesque design, it is thought to be a decorative water spout. It is likely it was among parts of the original church building, dating from the 11th century, which were demolished and re-used when the church was remodelled and the tower added in the 13th or 14th centuries.

Mr Barker, who is also Great Yarmouth Borough Council's principal conservation officer, said it was a hugely exciting find.

'We have found bits of window tracery and door jams in the fabric of the ruined church, but to find a figurative carving is particularly special,' he said.

'This is the artwork of a nameless stonemason, who lived and died a millennium ago, which had lain hidden about 50 ft above ground for most of its existence, so it is a fantastic chance discovery and extends our understanding of the church and this period of history at Hopton.'

Mr Barker explained that as Norfolk did not have a local source of building stone, and moving stone long distances across rudimentary roads was difficult, it is likely the limestone for the head was shipped from Caen in France, like stonework for many other historic buildings across Norfolk.

'This also explains why stonework like this was often re-purposed over the centuries,' he added.

The preservation trust hopes to be able to put the head on display and plans to use a drawing of it as the logo of its new consultancy arm, Norfolk Conservation Ltd.

The work on Hopton's church tower is being carried out over 10 weeks by specialist contractor, Medieval Masonry Ltd.

The wider project is supported by the Heritage Lottery Fund, English Heritage, the Pilgrim Trust, Hopton Parish Council, Great Yarmouth Preservation Trust, and Great Yarmouth Borough Council.