Lust For A Vampire by William Hughes

Novel actually 'based on the screenplay' of the 1971 Hammer film, directed by Jimmy Sangster (stepping in after Terence Fisher broke a leg) , starring Ralph Bates, Barbara Jefford, Suzanna Leigh, and introducing as Carmilla/Mircalla that delectable Dane, Yutte Stensgaard, who expresses her deepest passions by going charmingly cross-eyed. This film -- sequel to Hammer's 1970 blockbuster 'Vampire Lovers,' with Ingrid Pitt. and also scripted by Tudor Gates -- was notable for the odd soundtrack song 'Strange Love,' which unfortunately cannot be heard as you read the book, though presumably you could hum along