Sleaford Castle

Sleaford Castle stands on flat fenland near the River Slea in Lincolnshire. Built in the 1120s by Alexander de Blois, Bishop of Lincoln, it was a square castle with four towers and a large keep. The bishop chose the site deliberately, replacing an earlier moated manor house. A 40-metre tithe barn once stood in the southern half, said to be England’s largest. A watermill powered by a dam on the Slea produced grain for the area. The castle never faced a siege but twice had to surrender its keys. King John spent his last night here in 1216, days before he died. Henry VIII stayed twice, once with Catherine Howard in 1541, and held a State Council here. By the 1550s it was still habitable, but lead and timber were removed for town buildings. By 1604 it was described as ‘the late fair castle’, already dismantled. Today only a moat, a small toppled wall and earthworks remain. A scheduled monument, it is managed for wildlife and occasionally excavated. In 2023 archaeologists found a floor tile with a cat’s paw print and a 16th-century German jetton. Visitors walk around the quiet grassy banks and imagine the bishops and kings who once stood where the wind now blows.