Lee Thompson gained his first international experience in 2017 when he won the gold medal in the British 4 x 400 meter relay in 3: 03.65 minutes at the U23 European Championships in Bydgoszcz . The following year he reached the semifinals over 400 meters at the World Indoor Championships in Birmingham and was eliminated there with 47.14 s, while he finished sixth in the relay in 3: 05.08 min. In 2019 he won the silver medal behind the German team at the U23 European Championships in Gävle in 3: 04.59 minutes and took part in the relay team at the World Championships in Doha at the beginning of October , where the British relay reached the final , where it races but couldn't finish.
In 2018 Thompson became British indoor champion in the 400-meter run.
Personal best
400 meters: 46.40 s, August 14, 2019 in Manchester
400 meters (hall): 46.23 s, February 18, 2018 in Birmingham