He was out of the mare Mintwina, who was also the dam of Morrissey's Canadian Horse Racing Hall of Fame inductee, Bunty Lawless.
Roselyon was a son of the 1911 Epsom Derby winner and British Horseracing Hall of Fame inductee, Sunstar.
Trained by Gordon McCann, the oft-injured colt did not race at age two but as a three-year-old won three times in ten starts.
Ridden by Ronnie Nash, in the May 18, 1940 King's Plate Willie the Kid beat a field that included Curwen, the Harry Hatch-owned colt who had been sent off as the betting favorite.
In the ensuing Prince of Wales Stakes, Willie the Kid again beat third-place finisher Curwen but was second to race winner, Hood.