From its modest beginnings in 1909 to the end of the Second World war, MI5 was at the centre of the struggle against Britains enemies.

Many of its exploits are here described for the first time - and some of MI5's true stories are as bizarre as any fiction conjured up by Le Carré or Deighton...

The wireless transmitter deposited by Robert Petter at the left luggage office of Waverly Station, Edinburgh in September 1940. This photograph was taken by the Edinburgh CID before passing the radio on to MI5. Peter was arrested as he tried to reclaim his suitcase.