B/W movie, thriller, couple birtish actors in it.

Many years ago I saw a film. Plot was young man meets woman ands asks her to marry him. She wont till he come to meet her zany family. The one that I remeber the most is the uncle who believes the end of the world is coming and he has to save two of every animal to repoplate the world inculding man. He trys to cage the young man and another girl in his cage for the end of the world. He has even built an Ark. theres another uncle who has a british accent. Very heavy set and I know at the time he was fairly well know for mystery movies. Through out the movie it is rainning to the exstream.
I was told once it was the old dark house but that one is way older and had Boris Karloff in it. Pleae help.