Rowing (lightweight double scull)
Purchase won Olympic gold in Beijing with Mark Hunter, Britain's first-ever lightweight Olympic medal.
He won the single scull at the 2006 World Championships and the double sculls with Hunter in 2010 and 2011.
Having set the world's best time in the lightweight single scull in 2006, he teamed up with Hunter in the lightweight double scull the following year.
His 2009 season was ruined by a virus - while Hunter took the year off - and Purchase was then unable to compete for four months in mid-2011 due to post-viral fatigue.
Cheltenham-born Purchase, who will marry his fiancée Fliss two weeks after the Olympics, got into rowing at school in Worcester - initially too young to row, he offered his services as a cox until he was able to sit in a crew boat.