Burwell "Bumpy" Jones, a member of the 1952 US Olympic team, began swimming in Masters in 1972. See his International Masters Swimming Hall of Fame, "Burwell 'Bumpy' Jones (USA) 2005 Masters Swimmer" story.
SWIMMER magazine (March-April 2005, Vol. 1, No. 1) details a historical perspective of Burwell "Bumpy" Jones' early 1950s butterfly stroke in the Splashback article "Butterfly's Emergence Challenged 1950s Swimmers."