According to Official Guinness Records,
The fastest throw of a rugby ball was 48.0 mph (77.25 km/h) and was achieved by Joe Simpson (UK), a professional rugby player for London Wasps, in an event organised by EMC (UK & Ireland) in London, UK, on 14 April 2011.The event was organised by EMC, the official sponsors of London Wasps rugby team, to promote their forthcoming St George's Day game.5 professional rugby players (ex and current London Wasps) competed against each other in a face-off challenge and each player had 6 attempts. The players were Nick Berry, Kenny Logan, Tom Varndell, Mark Robinson and Joe Simpson.4 players exceeded the minimum requirement of 40 mph, but Joe Simpson achieved the fastest speed of 48.0 mph and was awarded the record.The rugby throws were carried out in a speed cage to measure the speed of the ball.
For a complete list of 2011 records, please visit 2011 Guinness Records in United Kingdom.