To quote from The King’s Works p.688 and Pipe Roll 31 Henry I, p.31: 'the outlay in 1129-30 of £11 in operationibus Regis de Chernardesburgh is the earlest proof of its (the castle’s) existence.’
Waterman (1953) describes remains from what ‘appeared to have been a 12th c. horizon on the then castle site'.