Prescot, Lancashire born goalkeeper Billy Mercer started his football career with junior club Grosvenor in 1908 and joined hometown Prescot Athletic in 1909, spending 1910-11 on the books of Second Division Huddersfield Town without making their first team. He continued to play for Prescot Athletic, until like his unrelated namesake David Mercer, he moved to Second Division Hull City in August 1914, making his Football League debut at Clapton Orient in January 1915. It was his only appearance before peacetime football was suspended due to the onset of the First World War, during which he served throughout with The Royal Engineers and he guested for Stockport County in 1918-19.
After the conflict he resumed with Hull City winning the goalkeeper’s gloves undisputed from Nick Hendry in January 1920 and being described as “exceptionally able”, missing 5 games in the next four seasons, during two of which he was an ever present, before signing for Herbert Chapman’s League Champions Huddersfield Town in November 1924 after 203 appearances for The Tigers.
He played 28 games as The Terriers retained the League Championship in his debut season, and although he lost his place to Ted Taylor he still played 13 times as they won the hat-trick of League Championships in 1925-26. He remained at Leeds Road and reclaimed the goalkeeper’s gloves in November 1927, keeping goal for The Terriers during their 1928 FA Cup run that saw them beaten 3-1 in the Final at Wembley by Blackburn Rovers in a season in which they also finished runners up in the League Championship. It proved Mercer’s penultimate game for Huddersfield and after 79 appearances he moved to Blackpool in May 1928. He played 19 times for The Seasiders before retiring in the summer of 1929.