The BBC TV science fiction drama (for children and adults) Doctor Who broadcast an episode entitled Churchill War Rooms museum, near Downing Street, which is full of formerly Top Secret maps, plans, telecommunications and cryptographic equipment etc.
The programme featured Winston Churchill and some Daleks in British Army uniforms (including webbing belts and water bottles etc.) and a striking Propaganda Poster, which can be downloaded from the BBC Doctor Who website as a (.pdf)
However, it appears that the Daleks were not the only alien invaders, as the text at the bottom of the poster appears to be quite odd. Note the American spelling of "Defense" rather than "Defence" and the lack of spaces after the commas.
Printed by the MOD Ministry of Defense Room 73,Public Relations Office, Fillongley Warks. Test Print awaiting approval,Not for public display until further notice.
Fillongley is in North Warwickshire, near to Coventry.
N.B. Neither the "Ministry of Defense" nor the "Ministry of Defence" actually existed during World War 2, they were called, perhaps more accurately, the War Office , the Admiralty and the Air Ministry.