In the United States, members of his mother's family have been major figures in the sport of thoroughbred racing for many decades. In England, Raymond Guest's sister, Diana Guest Manning, owned and raced a horse she named Be My Guest who was a conditions race winner in England and Ireland as well as the Leading sire in Great Britain and Ireland in 1982. Raymond Guest also owned thoroughbreds which he raced in England, Ireland, France and the United States. In Ireland his flat racehorses were trained by Vincent O'Brien and his National Hunt horses by Dan Moore. His racing colours were chocolate, pale blue hoops and cap. Guest is one of only four owners to win both The Derby and the Grand National, the others being King Edward VII, when Prince of Wales, Dorothy Paget and Jim Joel.