The castle continued in the ownership of Hamelin Plantagenet's family, passing to his son William de Warenne in 1202. William was probably responsible for the construction of new stone curtain walls around the inner bailey, destroying the former earthwork defences in the process. The inner bailey was levelled and William built a hall and service buildings inside the castle, again in stone. Conisbrough was inherited by William's young son John de Warenne in 1239, but he was still a minor and the castle was initially managed by his mother, Maud.