[6] Initially, Duff retained his amateur status with Huddersfield, but he turned professional in September 1926.
He came close on one occasion: with undisputed first-choice outside-left Billy Smith absent on representative duty with the Football League XI, Duff would have been the obvious replacement, had he not been injured.
[8] Duff moved on to Third Division South club Bournemouth & Boscombe Athletic, for whom he made his Football League debut during the 1928–29 season.
[1] Ahead of the 1930–31 season, Duff joined Third Division Darlington on a month's trial.
[9][10] He scored for the reserves,[11] and played twice in the league[1] – he hit the post near the end of the match after Darlington let slip a two-goal lead against Hull City,[12] – but was not taken on permanently because of what the Northern Daily Mail called the "brilliance" of Peter Bell and Reuben Vine.