Drawings of WW2 exploding chocolate bar bombs discovered
30 September 2015 Last updated at 07:50 BST
Drawings of wartime booby trap bombs, including an exploding chocolate bar and devices intended to sink ships have been rediscovered after 70 years.
The designs were made by a young artist called Laurence Fish, for MI5's counter-sabotage unit.
Nick Higham has had an exclusive look at them.