German writer Timur Vermes examines how the BBC used humour throughout the war to counter Nazi propaganda.

Historians have pored over Joseph Goebbels and his reputedly efficient propaganda machine - particularly the Nazi manipulation of radio to gain and maintain power. But few have explored the leading opponent of his propaganda - the German Service of the BBC.

Fewer still have acknowledged that the BBC's radio transmissions to Germany contained not only news and comment but also drew on an unusual method of British psychological warfare, satire and humour, as a form of counter-propaganda.

From mid-1940 until the very end of the war, pioneering satire feature programmes were written by German exiles under the close supervision of British authorities.

They included Frau Wernecke - a sketch fronted by a fictional Berlin housewife; Kurt and Willi - a double act depicting two bungling Nazi propagandists; and Letters from Corporal Hirnschal - a soldier writing to his wife. Meanwhile another popular feature, Hitler on Hitler tried to point out inconsistencies in the Fuhrer's rhetoric.

What did the authors of these programmes, the BBC officials and the relevant governmental institutions hope to achieve with satire as a weapon of war?

Timur Vermes pores over the archive with experts, hears testimony from those who risked their lives listening to the satire, and tries to work out if satire is effective as wartime propaganda.