A couple of villages up the coast from where I grew up is the motte and bailey of
Skipsea Brough, which can be seen from the main road to Bridlington, the impressive motte looking like a mini-Silbury in the flat East Yorkshire landscape. The site has its own ghost too, Lady de Bevere, the niece of William the Conquerer. She was married to Drogo de Bevere, who had fought at Hastings and been rewarded by William by being given Skipsea, as well as his niece's hand.
Drogo, for unspecified reasons beyond being a cruel husband, fatally poisoned his wife, and immediately hot-footed it back to mainland Europe to escape William. Since then, the ghost of a lady in white has been seen around the castle's remains, believed to be Lady de Bevere.
When I was at school, a girl from Skipsea in my class once said that she'd seen a ghost at the Brough; a white figure that came through a hedge, crossed the road and then vanished. She was one of those "hard" girls (a sort of prototype for Tasha Slappa from Viz), and not the sort of person you'd think would admit to something like that for fear of ridicule (teenage girls being the most terrifying peer group in existence, IMO). She didn't seem to know about the legend, but when I started telling her about it, she just said "Shurrup!", because it scared her!