Before Julian Assange, the WikiLeaks founder, and Edward Snowden, the intelligence whistleblower, there was Katharine Gun. The former GCHQ employee ... was a young Mandarin specialist at the British government's eavesdropping agency in Cheltenham. In early 2003 she received an email asking her and her colleagues to help the US government spy on UN security council delegations in New York. It was a critical moment, as Washington was seeking UN backing for its invasion of Iraq. Gun decided the world had to know, whatever the cost to her life and career. She leaked the memo to the Observer and was arrested, lost her job and faced trial under the Official Secrets Act. Thirteen years later, as bloodshed continues in Iraq, the almost forgotten story is to be brought to a new audience in Official Secrets, a movie [that] will chart Gun's unlikely bid - courageous self-sacrifice to supporters, treachery in the view of critics - to block George W Bush and Tony Blair's march to war. Unlike many whistleblowers who leak thousands of documents after the event, Gun was intervening in an active operation and trying to stop a war. The US National Security Agency memo told employees of GCHQ to gather the whole gamut of information that could give American policymakers an edge in obtaining results favourable to US goals or to head off surprises". "I saw the email and my gut reaction was pretty instantaneous, that it was highly explosive information and that it should be out in the public domain," she recalled.