With the BBC's iconic wartime comedy Dad's Army entertaining cinema goers, Helen Castor sets out to find if this view of a rather amateurish war effort, in which the British won through against the odds, is really true. She's joined by historian James Holland who argues that Britain's military victory came about through science and industrial expertise that was actually well ahead of the Nazi's. She's also joined by Dr Chris Smith who claims this is true also in the rigorous approach used by the codebreakers at Bletchley Park.