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D-Day double crossing

25 March 2012 Last updated at 11:48 BST

Author and historian Ben Macintyre tells Andrew Marr how a tiny, secret unit of spies, including a "bisexual Peruvian gambling girl" and a "failed Spanish chicken farmer with a wild imagination" helped ensure victory on D-Day, the turning point of the Second World War.

Macintyre's book 'Double Cross: The True Story of the D-Day Spies' tells the story of these double agents, who he calls the "oddest military unit ever assembled".

You can watch the Andrew Marr Show in full on the BBC iPlayer