Bristol born inside right Billy Gerrish began his football career with Freemantle, from where he joined hometown Southern League Champions Bristol Rovers in 1905. He scored 11 goals in 49 appearances for The Gas over the next four seasons and was signed by First Division club Aston Villa in April 1909, making his Football League debut, scoring in a 5-1 victory over Woolwich Arsenal on 1st September. Gerrish scored a hat-trick in his next home match in a win over Chelsea and contributed 15 goals during the campaign, missing just two matches as Aston Villa won the League Championship.
He played in the 1910 FA Charity Shield in which Aston Villa lost 1-0 to Southern League Champions Brighton & Hove Albion at Stamford Bridge that September, however he lost his place in October after 7 matches as Villa defended the League title, finishing runners up to Manchester United, and played just 8 matches during the second half of the season, and five matches during the whole of the 1911-12 campaign, before joining Second Division club Preston North End in May 1912 after 18 goals in 59 appearances for Aston Villa. Although Preston won the Second Division Championship that season, Gerrish played in only 3 matches in the autumn, and joined Midland League club Chesterfield Town before the year end, where he appeared 8 times for The Spireites during the remainder of the season., before finishing with professional football.
In February 1915, six months into the First World War, Gerrish enlisted in the Footballers Battalion, the 17th Service Battalion of the Middlesex Regiment. He was severely wounded in both legs by a shell blast at Delville Wood on 8th August 1916 and died later that day, aged 32. Gerrish has no known grave and is commemorated on the Thiepval Memorial.