He also played league football for Hull City and Torquay United and won two caps for England.
After beginning his career in non-League football with Prescot Athletic, St Helens Town and Skelmersdale United,[3][4] Mercer joined Second Division club Hull City for a £40 fee on 22 January 1914.
[2] He made 91 league appearances and scored 26 goals for the club before moving to First Division Sheffield United on 13 December 1920, for a British record transfer fee of £4,500.
[2] He made 241 appearances and scored 22 goals for the Bramall Lane club and won the 1924–25 FA Cup, before leaving in 1928.
[1] Mercer represented the Football League XI and won two caps for England, scoring once, in a 6–1 victory over Belgium on 19 March 1923.