My father went down much the same route, tried to enlist in 1914 aged 15 because he was "Bored" by farm life, but gave the correct age, was told to come back the next year "And don't be 16". In WW2 he was in the reserved occupation as railway engine driver, but Sergeant in the Home Guard, and from information I stumbled across when he died I think he might have been designated as a "stay behind", but that was never talked about and today is still somewhat shrouded.