Yes. This is taken from "Wembley Speedway the Pre-War Years", available from all good book shops, Amazon and the author!
"Putt Mossman...put on an interval display. Mossman decided to perform, as his finale, a motor cycle striptease act. Standing on the saddle of his bike he removed his jacket, shirt and trousers. He appeared to be standing on his bike naked, although he was, in fact, wearing a skin coloured pair of briefs. The next day when he went to collect his money, the straight-laced Elvin told him he was banned from ever appearing at Wembley again."
The Billie Smith story is also featured in the book.