Rachel Ayrton won bronze in the 1,500m under-15 category at the Middlesex County indoor Athletic Championships.
Taking part in her first competitive athletics event, Ayrton, 13, came home in third place in a time of 5:31 at Lee Valley Stadium in Edmonton.
A pupil at Northwood College, the versatile Ayrton will be the youngest member of the Team GB swimming squad at the 19th Maccabiah Games this summer.
As part of her training for Israel, she trains six days a week, covering up to 25,000m in the pool with her swimming club Hillingdon SC.
Ayrton said: “I think my strength from swimming really helped in the final stages of the race.”