A form of hard chalk used as a building stone. The mains sources of this material were on the north-west edges of Suffolk – at Lakenheath on the fen-edge, at Thetford in Norfolk and at Burwell (‘Burwell stone’), Orwell and Barrington (‘Barrington stone’ a grey-green variety with glauconite) in Cambridgeshire. lthough hard enough to be worked into blocks, it was still susceptible to rapid weathering if exposed. So, for external walls, its use was mainly limited to vernacular buildings in its source areas, as can be seen in Lakenheath. In many cases it was combined with flint or brick to make more durable structures But it was also more widely used in medieval church interiors, where the material’s softness could be protected from weathering and exploited for richly carved decoration, as in Wingfield church.