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An unprecedented look inside Britain's Secret Intelligence Service, which marked its centenary in 2009.
BBC security correspondent Gordon Corera talks to senior intelligence officers, agents and diplomats as well as their former arch enemies about the shadowy world of espionage.
Part Three - New Enemies
What is the role of MI6 in the 21st century?
The former head of Britain's Secret Intelligence Service talks about the interrogation of terrorist suspects and MI6's role in the run up to the war in Iraq.
This is an updated version of the programme that was first broadcast on the BBC World Service on 26 October 2009.
Originally broadcast on BBC Radio 4.
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