Moreover, off-field from 1946 to 1949 he re-introduced the R.C. Hamilton tactic of the false number-nine, notably with that centre-forward being a certain Don Revie Don Revie, who was to marry his niece, daughter of brother, Tom, also a professional footballer with Leicester, Halifax Town, Bristol Rovers and later Leicester coach. 

Johnny and Tom Duncan were both born, the former in 1896, the latter in 1899, and brought up in Lochgelly, sons of a coal-miner born in Donibristle by Aberlour and a local mother. And Johnny, at least, would during The Great War follow his father down the pit, whilst beginning his football from 1915 with Lochgelly United, as an inside-right. But he clearly showed talent and when league football restarted in 1919 he both moved to Raith Rovers, signed by Peter Hodge, and was part of the team that in 1921-22 finished fifth in the top-flight. 

By then he had been joined at the Kirkcaldy club by brother, Tom, an outside-right, and in the summer of 1922 not one but both would be signed by Leicester City, the manager of which was now the same Peter Hodge. Thus it was that twenty-six year old Johnny, for now still at inside forward, would go straight into the team making forty-three appearances and Tom, three years younger, would make twenty-nine starts.   

But in 1923-24, whilst Johnny continued to be a first-team regular, Tom would play only thirteen times, Hugh Adcock preferred and in the summer he moved on, to Halifax Town for two seasons, then Bristol Rovers for one more before a finish, aged twenty-nine, back in The Midlands but outwith the League with Kettering Town. And he did it as a married man. In Bristol he had wed Jane Leonard with whom he would have four chldren, the family eventually settling back in Leicester, where he still had business interests with his brother.     

Meantime, Johnny, who in 1922 before heading South had in Dunfermline married Airdrie-born Margaret McQuiston and with whom he would have three children, would continue to play at Filbert Street until 1930, latterly as captain, in 1925 scoring in winning a single cap in a forward line that also included Alex Jackson, Hughie Gallacher and Alex James and from 1928 having dropped back to right-half. However, he is then said to have fallen out with the club because he took over the licence of a local pub, The Turk's Head,. It seems spurious. He was by then already thirty-four, was clearly forceful and more likely it was decided the time had simply come.