The Grass is Greener - 1960 ****1/2

An amusing and typically English film. Cary Grant and Deborah Kerr are the owners of a large stately home which they periodically open to visitors for extra money. One day Robert Mitchum appears and falls in love with Kerr, who reciprocates and rushes off to London with him for a few days under the pretence of visiting friends. Meanwhile, Grant (fully aware of the situation) has the pleasure of an old friend (Jean Simmons) who drinks too much, flirts too much, and is besotted with him.
It's quite farcical but very enjoyable and easy going - must watch.