Relatively Speaking

Greg and Ginny are a young couple living in a bedsitter in London and wanting to get married.  Some forty miles away in rural Buckinghamshire live Philip and Sheila.  Apart from the fact that Philip and Ginny have had a brief affair, the couples are not related, but they are brought together when Greg suddenly visits Buckinghamshire in the belief that Philip and Sheila are Ginny's parents;  later Ginny arrives there too.