This is a Gordon Jarvis stamp and Gordon Jarvis was a turf accountant which is a British term for a bookmaker, specifically one who accepts and pays out bets on horse racing and greyhound racing. The term "turf" refers to horse racing, which traditionally takes place on grass tracks, and "accountant" refers to the person who handles the money and bets. 

After doing some research this stamp has now kindly been returned to his daughter.