Winnington, Cheshire born outside right Alfred “Freddy” Capper began his football career with Northwich Church Lads in 1909 and joined Northwich Victoria in 1910, before signing for First Division Manchester United as an amateur in January 1911, where he made only one first team appearance, a 1-1 draw against Liverpool in March 1912. Capper, one of three debutants in the match for United, was later criticised for holding onto the ball too much and failing to use his pace to beat opposing defenders, before being released at the end of the season, joining Lancashire Combination club Witton Albion in May 1912.
During the 1913-14 season he was part of the Witton Albion side that won the Lancashire Combination Second Division. He then signed for First Division club Sheffield Wednesday in April 1914, making 25 appearances and scoring 4 goals in the 1914-15 season, the final season prior to the suspension of peacetime football due to the onset of the First World War.
During the War he was a corporal in The Royal Engineers, and after the return to peacetime football in 1919 he resumed with Sheffield Wednesday making a further 37 appearances without scoring before moving to Third Division (South) club Brentford in August 1921. On 11th February 1922 in their match at Newport County, Capper became the first Brentford player to be sent off in the Football League, receiving his marching orders from referee and future Brentford manager Harry Curtis. Described as “a player of fine physique, he is difficult to knock off the ball and can centre well from the touchline”, he was a regular for The Bees over his three seasons at Griffin Park, making 106 appearances and scoring 6 goals before his retirement from the game in 1924.