How MI5 won the intelligence war
The contents of this book were kept secret for over 50 years and when John Curry's report was released to the British National Archives they immediately turned it into a book. Sadly it is now out of print and only used copies occasionally become available. The best thing about this book is that it was written in 1946 by a man who was directly involved, amongst other things, with Britain's intelligence war with Germany and the famous Doublecross program in which a huge network of German spies in Britain turned out to be wholly run from the offices of MI5. It represents a valuable resource to anyone interested in WW2 intelligence and strategic deception.
Another contemporary, day by day account of MI5's WW2 work is the Diaries of Guy Liddell* who ran the department involved. Both books score 10 out of 10 for those interested in accurate detail and a story so fantastic you couldn't make it up.
*still in print