Jemma made her Commonwealth Games debut at Birmingham 2022, after a meteoric rise in the sport over the preceding few years. European Junior champion in 2017, she went on the secure a rare 800m and 1500m double at the European U23 Championships two years later.
It was February 2020 that perhaps provided the true breakthrough moment with a 1.57.91 clocking in Glasgow for a new British indoor record, a time that astonished everyone, including herself, and put her firmly in the realm of world class 800m running. Just a week later she added two more British indoor records - running 4.17.88 for the Mile at the Millrose Games in New York, USA, her split time of 4.00.56 at 1500m also a national best.
She made her Olympic debut at the delayed Tokyo 2020 Games in the summer of 2021, finishing 4th in the 800m final in a personal best time of 1.56.90. At Birmingham 2022 she competed in the 800m and 1500m, her best result coming in the latter with fifth place in the final. She went on the finish fifth in the 800m final at the 2022 European Championships.