[2] Williamson, a London native, is the second cousin to 2008 Beijing Olympics silver medalist British high jumper Germaine Mason.

[5] He won the silver at the European Junior Championships in 2005, 1/100 of a second behind Craig Pickering, to complete a British 1–2–3 with third placed Alex Nelson.

That year, Williamson was featured in a BBC documentary called Sprint, along with other 100 m hopefuls Pickering, Harry Aikines-Aryeetey and Wade Bennett-Jackson.

[6] He was selected to compete at the European Indoor Championships in Turin and finished a close fourth in the 60 m final with 6.57 s.[7] In the outdoor season in June, Williamson ran the 100 m in 10.09 seconds at the Fanny Blankers-Koen Games.

[10] Williamson was pleased with his first national title, having finished as runner-up a number of times, and turned his attention to a further Golden League meet against Usain Bolt.

He stated that he was not sure how he had managed his 10.05 seconds win, but announced that he would return to Jamaica for a winter training camp to try to improve his consistency for the following season.