Born in Tompkins, Saskatchewan in 1923, John began his tennis career in Saskatoon. At the age of 17, he captured the Saskatchewan junior singles title. The following year, his athletic ability was observed in Western Canadian and Canadian championships. John, who was also an outstanding minor hockey league player, took a break from competitive play to serve in the RCAF in 1942 and 1973. When he returned to the game, John won the Saskatchewan championship seven times in singles, nine times in doubles and six times in mixed doubles.
In 1980, Leicester was a Canadian finalist in the 55 years and older category and was named to the Canadian team that competed for the Austrian cup. Two years later, he was ranked third for Canadian senior. In 1983, he was rated fourth in singles and first in men's doubles.
Even while competing, John found time to serve the sport in several administrative positions and was responsible for organizing the Saskatchewan Junior program. He has written two tennis booklets.
John was inducted into the Saskatchewan Sports Hall of Fame in 1984.