Piano piece in The Alien Corn (Quartet)?

I have listened to a piano piece I find very beautiful, but unfortunately I could never find out who has composed it. I recently heard it again in a short movie called "The Alien Corn" with Dirk Bogard, this movie is part of "Quartet" which is a collection of short stories, written by W. Somerset Maugham. The guy plays this piece in the scene where his cousin visits him in his appartment in France, and he plays it for her, he then gets very upset and sais that it wasn't one of his best days. Could someone help me out? Thanks!