The Second World War took a heavy toll on the members, with 49 losing their lives. So weakened was the club that it merged with its oldest of rivals, Old Whitgiftians, for a year in 1945. A modest resurgence took place at the turn of the decade, with Ian Coutts gaining his Scottish caps, and the likes of London Irish, London Welsh and Wasps falling to the OAs. However, by the late 1960s the OAs played strong local opposition rather than "1st class" clubs. In the 1980s the club continued to be strong, arguably the strongest of all Old Boys clubs in London, with the topping of the Combined London Old Boys Merit Table in 1988 as testament to this. In 1987 the league system introduction led to the club being placed in the Courage League London South 2. In 1989 the club were promoted to London One, won the Surrey Rugby Union Cup, topped the Combined London Old Boys Merit Table once again and qualified for the Middlesex Sevens Finals.