Walker, Newcastle born centre half Bob Fenwick played football for North Eastern League club Ashington in 1919 before signing for Lincoln City, for whom he made his first-team debut in the Midland League in August 1920. He was ever-present that season, as Lincoln won the Midland League title and were elected to the new Third Division (North) section of the Football League.
After 2 goals in 51 League and Cup appearances during their League seasons, Fenwick joined Second Division Notts County in February 1923, playing three times as the club were promoted to the First Division as Second Division Champions at the end of the season. However he was unable to establish himself in the first team, and played only three times in the top flight before returning to Lincoln City in February 1925. He made another 27 appearances for The Imps, then moved into non league football successively with Shirebrook in 1926, Newark Town in 1927, Horncastle Town in 1928 and Shildon in 1929 before his eventual retirement.