This webpage by Brian Billington
sisyphus.demon.co.uk/POTOC/png/2000-03.potter.TC.html
says that an 1899 map calls the fort ‘Wulferecester’ – Wulfere’s town. There’s a mound inside the southern part of the enclosure, which is said to be the site of the palace of Wulfere, the Saxon King of Mercia.