The Haunting of Hiram- Eva Ibbotson

‘I will buy your castle,' declared Hiram C. Hopgood. ‘But only if there are no ghosts!' Alex MacBuff can't afford to keep his beloved Castle Carra - and an American millionaire has made him an offer he can't refuse. But the castle is full of ghosts! There's Krok the hairy Viking warrior, mad Miss Spinks, a hell-hound called Cyril, and a vampire with no teeth. How can Alex stop them haunting Hiram?