Of the original cast of Alegrias a Granel (1949), only Catherine Lacey, Jean Cadell, Duncan MaCrae and Gordon Jackson reprised their original roles.
Roland Culver plays Captain Waggett. Basil Radford, who had played Captain Waggett in Alegrias a Granel (1949), passed away in 1952.
Vehicles/aircraft include . . .
David Brown 50TD (Trackmaster) diesel crawler (bulldozer).
Land Rover Series I, original 80-inch wheelbase model.
Bristol Sycamore (helicopter).
Blackburn Beverley (4-engine heavy transport aircraft).
Bristol Bloodhound (ramjet-powered radar-homing ground-to-air missile).
During the political discussion towards the end, one participant is Michael Foot who was a Member of Parliament 1945 to 1955 and 1960 to 1992 (so wasn't when the film was made) and who became Leader of the Labour Party. Another was Robert Boothby who had also been an MP and was elevated to the Peerage soon after this film was made.
The Free Speech panel were WJ (Bill) Brown MP, Robert Boothby MP, Michael Foot and Professor AJP Taylor. The panel was chaired by Edgar Lustgarten.