Hamsterley, County Durham born left half Alf Fenwick had signed for Second Division Hull City in 1910 from junior club Craghead United and made his Football League debut for Hull at Nottingham Forest in December 1911. His opportunities at Hull were limited and despite 7 goals in his 17 appearances, 5 of which came in 4 games at centre forward in April 1913, he joined Southern League club West Ham United in April 1914, making his West Ham debut against Gillingham at the start of the following season, in which he scored once in 21 games before peacetime football was suspended due to the onset of the First World War.
He played wartime football for West Ham and guested for Hartlepools United and briefly resumed with The Hammers at the start of the 1919-20 season, playing in their first two Second Division games of the season including their inaugural Football League match against Lincoln City in August 1919, before joining Coventry City in December 1919. After a goal in 53 appearances in his season and a half at Coventry, he returned to non league football in the North East in the summer of 1921 re-joining Craghead United and playing for Blyth Spartans before returning to Football League action when he joined Ashington in May 1924. He made 12 League appearances that autumn before re-joining Blyth Spartans later in the year.
His son, also called Alf, played once for Reading in August 1939.