Six : the real James Bonds, 1909-1939

Six tells the complete story of the service's birth and early years, including the tragic, untold tale of what happened to Britain's extensive networks in Soviet Russia between the wars.

It reveals for the first time how the playwright and MI6 agent Harley Granville Barker bribed the Daily News to keep Arthur Ransome in Russia, and the real reason Paul Dukes returned there.

It shows development of tradecraftA" and the great personal risk officers and their agents took, far from home and unprotected.

In Salonika, for example, Lieutenant Norman Dewhurst realised it was time to leave when he opened his door to find one of his agents hanging dismembered in a sack.

This first part of Six takes us up to the eve of the conflict, using hundreds of previously unreleased files and interviews with key players to show how one of the world's most secretive of secret agencies originated and developed into something like the MI6 we know today.

The second part, published in Spring 2012, will tell the story from the outbreak of World War Two to the present.