I remember seeing an old British movie, say late 60's, about a group of people who go to a castle maybe to visit a friend and one by one they all get killed by some unknown thing that sucks their bodies dry of blood. It turns out to be a plant , like a huge vine that grows on the castle that lives on blood. I can't think of the name of it and I'd like to see it again if I can find it on DVD. Thanks for any help you can give me!

Not a British movie, but it sounds like Island of the Doomed. La isla de la muerte (1967) (http://www.imdb.com/title/tt0059215/)