Rayleigh is one of 48 castles mentioned in the Domesday Survey of 1086 and the only one in the county of Essex. The Survey records that Swein (other spellings are Sweyn, Sweyne, and Suen) built the castle in his manor. He was the son of Robert FitzWimarc, a Norman lord and favourite of Edward the Confessor (r. 1042–1066). Swein was one of the wealthiest landowners in post-Conquest Essex, and the Survey records that in 1086 his lands were worth £255. As Swein was the son of a favourite of Edward it is likely that he did not arrive with William the Conqueror in 1066, but was instead born in England. Most land owners with significant holdings at the time of the Domesday Survey had disjointed, scattered properties however Swein was one of the exceptions and most of his land was within the hund