What was the name of the leading actress who starred in Wish you were Here?

remember the film, some teenage lass shacks up with an old perv ...think it could be in brighton, and then she has bun in oven and her saying to folk is "up ya bum?!!" i think it won oscars and everything was supposed to be set just after the war i think. what is the girl called in real life and what was her name in the film? is one of those little things that is just annoying me.