Bristol born inside left Billy Pocock started his football career with Bedminster St Francis in 1913 before joining Southern League club Reading the following year. His career was interrupted by the onset of the First World War which forced the suspension of peacetime football in May 1915 and when peacetime football resumed he joined hometown Second Division club Bristol City in the summer of 1919, making his Football League debut against Bury that August.
Pocock top scored for The Robins with 14 League goals in 1920-21 as City finished third and narrowly missed promotion, however they were relegated the following season. Pocock then played 40 League matches in 1923-24 as they won the Third Division (South) Championship, contributing 7 goals. He played his last match of 255 appearances for Bristol City in April 1926, having scored 48 goals, before moving to Scottish League club St Johnstone that summer, where he spent a single season at McDairmid Park scoring once in 24 appearances for The Saints before returning to the West Country joining non league Bath City in 1927. He later played for Bedminster Down Sports in 1928, his last known club before his eventual retirement.