Dad's Army: The Lost Episodes - Season 1 Episode 2 -

Captain Mainwaring is told that he can promote one of the privates in the platoon to lance-corporal and he chooses Frazer as being the most efficient. Unfortunately this leads to a bitter rivalry between Frazer - who keeps dishing out charge sheets and becomes unpopular - and Jones, culminating in a fight between the pair of them, and ultimately Mainwaring has to return Frazer to the ranks.