There's a movie documentary which if I recall correctly is titled "The Fifth Beatle". It was put out either in the late 90's or earlier this decade. Anyway it's about Pete Best who was the original drummer in the Beatles before they became the Beatles and I think, for a short time after the name switch. He wasn't very good, but he was good looking, friendly with John and Paul, and his mother ran a hot club, the basement of her house, which catered to teenagers. The movie details Pete's story and makes mention of the bet of which you talk. I think the movie said Pete's mom bet 200 pounds, a lot more money in those days than now, to win on Never Say Die in the Grand National or the Cheltenham Gold Cup (the race which helped make Michael Dickinson legendary when he saddled first through fifth in a 1980s or so rendition). Anyway she took the proceeds and bought the new house and converted the basement to a club. And from there...