The only dit I know about Dunkirk is the one my old mum spins me. As a child, her adult neighbour was a reservist Pioneer Corp private. He worked what they called "on the drops" down on the river (basically discharging coal from railway into collier ships),he was probably a tough working man normal for the era. He was called up on outbreak and then caught up in the whole debacle of evacuation of the BEF. He returned to England so shell shocked and frightened that he was immediately discharged from the Army. Upon return home he then fled to his bedroom and remained within his own four walls, without leaving the house, for weeks on end. Finally, grandmother heard the slow playing of a piano next door (through the wall)...this was the pioneer, starting to return to a slow recovery. Using music to calm himself.
All films are only even 1% true representation of the utter horror war inflicts upon the ordinary British working man IMHO.