The setting of this film is somewhat mysterious. It appears to be England, but the radio has American voices instead of British ones; both the doctor and the barmaid have very English accents, but middle-European names; the police wear uniforms suggestive of eastern Europe (and carry revolvers in a holster); a politician is described as "Secretary of the Interior", a post which does not exist in the British government; there is a reference to "the President", rather than the Prime Minister; and the inn where much of the action takes place seems halfway between an English pub and an Austrian gasthaus.
This film is usually said to be set in England or Britain. But it seems clear that it is implied to be in an unnamed fictional country. The police and military are not wearing British uniforms. The vehicles have non-British license plates. The vehicles themselves are mixture of British and foreign types. Various ranks and titles are not those used in Britain. Even the payphone on the wall of the pub is not one that would normally be seen in Britain.
In addition to the curiously mis-matched national characteristics such as accents, uniforms, etc already mentioned, many of the cars are not British models and the official vehicle bearing the dignitaries to the inn has tricolor flags on its front mudguards, suggesting French or Italian nationality.
The military truck drivers are sitting on the right hand side indicating they are British vehicles.