INTK Supernatural movie

A woman meets a man (soldier?) at a bar/dance. They end up going back to a room (hotel I believe) and in the morning she wakes up and he is gone but there is seaweed in the bed. She goes to the beach.. It ends up that he died at sea in the war and this was a ghost. This film has been bugging me for ages but I don't remember much of it, possibly set in the past, maybe after WW2. Help please?

Possibly British, I watched it on British TV in the mid 90s so this is early 90s at the latest, possibly before. Maybe even part of an anthology movie, series like Twilight Zone etc .