I would think it's more the actual 2nd world wartime '39-'45. Note the heavy curtains behind the fireman to close the cab off and block out mustard gas. British Rail was postwar. Note the Southern Rail on the number plaque. Private railway, as they all were before then.the British have always had a thing for gas masks and anybody who wears them...., John Haigh, John Christie, British Rail. This may have been taken around that time.
True.Yes ,what ever it is there not very serious about it , the masks have no canisters, . Both Haigh and Christie were actively caring out their deeds during the war .