Secrets and spies: book takes a peek inside classified files of MI6

Mansfield Cumming, the monocle-wearing founder of MI6, made total secrecy the essence of his organisation. He would, one assumes, have been horrified at the unveiling yesterday of the secrets he and his successors cherished for 40 years – from plots to undermine Bolshevism to the use of agents' semen as invisible ink.

The first and – if the famously publicity-shy managers of the Secret Intelligence Service (SIS) get their way – only official history of the world's oldest foreign espionage organisation was unveiled yesterday. This led to a blizzard of disclosures about the derring-do and inglorious failures of Britain's spies who fought clandestine wars against the Soviet Union and Nazi Germany and foiled a plot to poison Winston Churchill's milk with anthrax.

The book, MI6: The History of the Secret Intelligence Service 1909-1949, was written by the Belfast-based historian Professor Keith Jeffery, who was granted unfettered access to the organisation's archives on the basis that his research ended at the outbreak of the Cold War. By contrast, MI5, the domestic security service, last year published its own officially sanctioned history which reached as far as the present day.

Sir John Scarlett, the former "C" or SIS chief who commissioned the book in 2005, insisted that the history was nonetheless a considerable concession by MI6 towards explaining its work. Speaking at a formal launch in the august surroundings of the Foreign Office, he said: "For MI6, this is an exceptional event. There has been nothing like this before and there are no plans for anything similar in the future."

Sir John batted aside suggestions that the book had been written to restore a reputation tarnished by the failures of intelligence during the Iraq war, saying that the internal debate about an official history predated the toppling of Saddam Hussein.

The 800-page book sets out to refute some myths about the intelligence service which, whether it likes it or not, will always be inextricably linked with its most famous (fictional) employee, James Bond. Indeed, Professor Jeffery – who said the depleted nature of the MI6 archive was due to SIS's need to find space rather than cover up any nefarious activities – insisted that the agency never had a licence to kill and had abandoned plans for an assassination campaign across France to ensure the success of D-Day in 1944.

Rather, the historian outlines how the service scored successes such as its supervision of the Bletchley Park code breakers during the Second World War and its efforts to sink Soviet warships during the Russian Revolution. But the Queen's University academic does not shrink from highlighting the more Machiavellian activities of MI6, including Operation Embarrass, a scheme to blow up empty passenger vessels and thereby disrupt Jewish refugees from Europe reaching Palestine in the aftermath of the Second World War.

The book also reveals details of the trade craft employed by MI6 agents, including the 1915 discovery that semen was impervious to methods of detecting invisible writing.

Professor Jeffery said: "This archive is the holy grail of British archives – it is closed tight to everyone, so when I got in there, I was like a child in a sweet shop. There are enough files there to tell the stories of the real people at the real sharp end doing real brave stuff."