town, Blyth Valley borough, administrative and historic county of Northumberland. It lies north-northeast of Newcastle upon Tyne on the northern edge of the Tyne and Wear (Tyneside) metropolitan area. Cramlington is a new town developed to provide alternative, diversified employment in a former coal-mining area. Nearby is the noted country house Seaton Delaval Hall, built in 1720 in classical style. Pop. (2001) 28,653.