Born in Wandsworth, London, Janet was originally a tennis player who played for Britain in the Wightman Cup in 1946. She quickly turned to squash and in 1948 and 1949 was a losing finalist against Joan Curry. In 1950 she won her first British Open title, beating Curry in the final. She went on to win the trophy for the next 10 successive years through to 1959. Persistent back injuries meant that she had to retire in 1960. She became the first chairwoman of the Women's Squash Racquets Association soon after.
Janet also found time to write a book in 1953 entitled Squash rackets for women.