town (parish), Amber Valley district, administrative and historic county of Derbyshire, England. It lies on the east bank of the River Derwent. Belper is probably a corruption of Beaurepair, the name given to his hunting seat (and variously spelled) by Edmund Crouchback, earl of Lancaster and son of Henry III (reigned 1216–72). Jedediah Strutt, inventor of an important ribbing machine, built the town's first cotton mills about 1780. The production of nails was formerly the staple industry of the parish, but it has given way to cotton and hosiery manufacture, with some engineering. Pop. (2001) 21,938.