Stockport, Cheshire born inside forward Billy Kellock began his career with hometown club Stockport County, however he didn’t make any first team appearances for the club, and moved to France, playing for St Brieux immediately before joining Southern League Plymouth Argyle in February 1913, for whom he made his debut at Northampton Town in April 1914. An inside or outside left, the Plymouth club handbook explained that “he has had considerable experience both in England and France” and that he is “a most prolific goal getter”.
Kellock made only a few appearances before the outbreak of war put his career on hold, although he did return to former club Stockport County as a wartime guest during the 1915-16 and 1918-19 seasons. He also guested for Burnley during the conflict, scoring 14 times in 21 games.
At the cessation of hostilities he returned to Plymouth and was the club’s top scorer during the 1919-20 Southern League campaign with 13 goals. However, he could not keep his place in the team when Argyle entered the Football League the following season playing just 6 matches and after 15 goals in 40 games either side of the War, he left Home Park for newly elected Third Division (South) club Aberdare Athletic in June 1921, where he scored 4 goals in 15 appearances in their maiden League season, playing in their inaugural League fixture against Portsmouth that August.
In July 1922 he joined Barrow, finding his form and netting 15 times in 33 appearances including a strike in each of his first three matches, before signing for non league Torquay United in 1923, where he finished as the club’s top goalscorer in the 1923-24 and 1924-25 seasons. He joined Poole in 1925 and played for Green Waves in Plymouth in 1926, and finished his career with St Austell in 1927.