The Second World War saw the role of espionage, secret agents and spy services increase exponentially as the world was thrown into a conflict quite unlike any that had gone before it.
At this time, no one in government was really aware of what MI5 and its brethren did.
But with Churchill at the country's helm, it was decided to let him in on the secret, providing him with a weekly report of the spy activities - so classified that he was handed each report personally and copies were never allowed to be made, nor was he allowed to keep hold of them.
Even now, the documents only exist as physical copies deep in the archives, many pages annotated by hand by 'W.S.C.' himself.
Here acclaimed intelligence expert Nigel West unravels the tales of hitherto unknown spy missions, using this ground-breaking research to paint a fresh picture of the worldwide intelligence scene of the Second World War.