Secret files reveal drunken meeting between Stalin and Churchill, a cross-dressing spy and King Edward VIII's phone bug.
Police investigating the death of MI6 code-breaker Gareth Williams are to intensify their inquiries into his colleagues and work.
Whatever the coroner's verdict today at the inquest into the death of MI6 spy Gareth Williams, many questions will remain unanswered.
The former head of counter-terrorism at MI6 has said he believes it would have been "incredibly hard" to prevent the killing of Drummer Lee Rigby in Woolwich.
Richard Barrett told BBC Two's Newsnight programme that two suspects "probably didn't have any intention to commit a crime like this until relatively recently".
I assume that these people are probably coming out of a small group without, necessarily, any overseas connections or any other broader connections in the United Kingdom which could come to the attention of the security services more than they did.
When does a person who expresses radical views, who joins a radical group, flip over to over to be a violent extremist?
To find the signals, the red flags as it were, I think is enormously hard.
Scotland Yard Commissioner Bernard Hogan-Howe says the review of Gareth Williams 'spy in bag' case is considering conducting voluntary mass DNA testing MI6 officials.
The papers say that 15 members of the security service have already provided samples.
There was one source of unidentified DNA found in Mr Williams flat.
On Gareth Williams an MI6 spokesman said: "At no time did we withhold any evidence".
This is the first time such a spokesman has been quoted as MI6.
The Metropolitan Police's Deputy Assistant Commissioner Martin Hewitt said they are trying to "trace unidentified DNA" to understand what happened to Gareth Williams.
He added that the case "remains a current investigation".
Following an inquest, a coroner can return a 'narrative verdict'. This is a factual statement of the circumstances surrounding someone's death, without attributing the cause to an individual. Narrative verdicts have been an option for coroners in England and Wales since 2004.
DCI Jackie Sebire has said that new lines of inquiry had come to light during Gareth Williams' inquest and that the investigation into his death is continuing.
In a statement delivered by solicitor Robyn Williams, the family of Gareth Williams said their grief was exacerbated by the failure of Gareth's employers, MI6.