This popular Ealing comedy is a first draft of national myth making about London's response to the blitz. The unexpected explosion of a dormant German bomb reveals buried medieval treasure... and a mysterious deed which indicates that Pimlico isn't part of Britain at all, but a fiefdom of the Duke of Burgundy...
And therefore isn't subject to the austerity laws of postwar Britain. So the locals all rip up their ration books and identity cards. The action is staged around a bomb site and the film builds a perverse nostalgia for the war, when people pulled together. The children are evacuated, and everyone makes do.
Given opportunity, leaders emerge, like Stanley Holloway who wants to use the windfall to develop social projects. Raymond Huntley turns his bank branch into the treasury. Margaret Rutherford shines as the excitable Professor who explains the historical back story. Ultimately the locals accept that deregulation leads to anarchy, and rejoin the UK.
There are the standard motifs of Ealing comedy, like the dreaded men from the Ministry, and the resourcefulness of the community, but the politics is muted. Though a shortish film, the interesting set up is overextended, and the satire is very gentle. However the ensemble cast makes it fun. Don't miss those Brexit parallels!