Reminds me of the story about when Di wouldn't let Charlie shag her until he got some contraception. He didn't really understand so he went to the nearest shop which happened to be a car spares place. He explained his situation and the guy at the counter asked when Di was born. He told him 1964. The guy then shouted down to his stores bloke 'Here John, have we got a coil for a '64 princess?'