He played at club level for Wakefield Trinity, as a wing.
[1] William Simpson played on the wing, and scored a try in Wakefield Trinity's 17-0 victory over Hull F.C.
in the 1909 Challenge Cup Final during the 1908–09 season at Headingley, Leeds on Tuesday 20 April 1909, in front of a crowd of 23,587.
[2] William Simpson played on the wing, and scored a try in Wakefield Trinity's 8-2 victory over Huddersfield in the 1910 Yorkshire Cup Final during the 1910–11 season at Headingley, Leeds on Saturday 3 December 1910.
[2] William Simpson played on the wing in Wakefield Trinity's 20-13 victory over Australia in the 1908–09 Kangaroo tour of Great Britain match at Belle Vue, Wakefield on Saturday 19 December 1908.