Working for the intelligence agencies is rarely as glamorous as it sounds, and until last year - when everything changed for ever - Katharine Gun often found it quite mundane. On Friday January 31 2003, at the high-security GCHQ compound on the outskirts of Cheltenham, she was doing her job as usual, translating Mandarin Chinese into English, when an email from America came to her attention.
"I thought, 'Good God, that's pretty outrageous'," she recalls. She printed out a copy, put it in her bag, took it home, and spent the weekend stewing about it. She didn't discuss it with anyone. On the Monday she was still just as angry - "indignation was fuelling me on," she remembers - and so she passed the email to a friend on the outside, whom she knew was in touch with journalists. But she heard nothing more, and almost forgot about it.
In February, as an opponent of the looming war, she travelled to London, to take part in the march. She bought books about Iraq. But it wasn't until a month later, on Sunday March 2, that a customer visiting Gun's local newsagent would have witnessed a small woman with shoulder-length blonde hair, holding a copy of the Observer newspaper and unable to stop herself shaking.
The email, splashed across the paper's front page, came from a US National Security Agency official named Frank Koza and was marked "top secret". As much of the world now knows, it requested British help with what amounted to a dirty tricks campaign: a plan for the bugging of offices and homes in New York belonging to UN diplomats from the six "swing states", countries whose support would be vital if Washington and London were to win a Security Council resolution authorising the invasion of Iraq. Within a week, Gun had confessed to her role as the leaker, left GCHQ, been arrested, and spent a night in police custody. Eight months later, she was charged with breaking the Official Secrets Act, facing the threat of a trial and a two-year prison sentence. Yesterday, at the Old Bailey, the case was finally dropped. The prosecution declined to offer any evidence, prompting speculation that the government was desperate to avoid being forced to reveal, in the course of a trial, details of its own legal advice on the war.
"I saw the headline and I was just going 'Oh my God, oh my God,'" Gun says. Today, standing in the cramped south London kitchen of the pressure group Liberty, which took on and fought her case, the 29-year-old is the model of composure. But at the time, she says, she felt physically sick. "This is my doing," she told her husband when she got home. She knew GCHQ would carry out an immediate investigation, and it did. The first time she was questioned, on the Tuesday, she failed to admit her involvement, but by the Wednesday her conscience was preying on her. She found her line manager and told her the truth.
Not many months afterwards, of course, David Kelly was to make a similar approach to his employer. But the style of GCHQ's response could hardly have been more different to the Ministry of Defence's. Gun's manager, she recalls, literally let her cry on her shoulder. "We're all humans at the end of the day. She could see how distressed I was. But she obviously knew what her professional duties were, and since I'd come forward, we went ahead and told the security division about it." More GCHQ officials - also "very nice" - took her to lunch in the canteen, as her friends looked on from other tables, wondering why she wasn't joining them as usual. Then she was driven in an unmarked car to Cheltenham police station and formally arrested.
Gun was to prove a particularly credible - and therefore, from the government's point of view, dangerous - kind of whistleblower. Unlike some earlier intelligence-agency leakers, she showed no signs of having been attracted to the job because of its cloak-and-dagger aspect. After spending much of her childhood in Taiwan, where her parents still live, she had studied Chinese and Japanese at Durham. Finding language work proved hard, she had responded to a newspaper advert for GCHQ. ("I didn't have much idea about what they did," she says today. "I was going into it pretty much blind. Most people do.")
Nor was there anything particularly complex about the case, from the point of view of public understanding ("Blonde who's likely to be a bombshell," screamed Bristol's Western Daily Press, arguably missing the point). You didn't have to be an international lawyer to smell the dodginess in Koza's email - although if you had been, you might well have decided that it seemed in clear contravention of the Vienna Conventions, which regulate global diplomacy.
The night in custody was bad enough. "The custody doctor prescribed a sleeping tablet, because I didn't think I'd get through the night without it," Gun says. But there were times during the months afterwards, waiting to discover if she would be charged, that were worse: "I'm a fairly happy-go-lucky person, generally fairly optimistic, but there were points when I was down. For about a week, I was really quite miserable. But I was on the phone to my parents almost every day, and they kept encouraging me, telling me I'm a survivor, all the rest of the stuff parents tell you to keep you buoyed up. So in the end I got through it. I was a housewife, I suppose, and luckily I have a very high boredom threshold." Eventually she enrolled on a postgraduate degree course at Birmingham University, studying global ethics. Some of her friends dropped all contact with her, but her "real friends", including some still working in GCHQ, are "still there".
When the charges came, she was shocked, she says - and scared about "having the whole government machine after you" - but still she did not doubt what she'd done. "Do nothing and die, or fight and die," she remembers her husband telling her, but the way she tells it, she never really had much of a choice. "I didn't feel at all guilty about what I did, so I couldn't plead guilty, even though I would get a more lenient sentence," she says. Of Koza's email, she explains, "I wanted to get it out. And I would do it again." A string of US celebrities stepped forward to urge the government to drop the case, among them the anti-war actor Sean Penn, the Rev Jesse Jackson, and Daniel Ellsberg, the leaker of the Pentagon Papers, who called the Koza email potentially more important than the documents he made public during the Vietnam war. Gun had her defence ready: she had broken the terms of the Official Secrets Act out of necessity, to prevent imminent loss of life in a war she considered illegal.
Her decision to follow her conscience sounds almost unthinking - "I didn't want to step back and think, 'But, hey, what happens if I do this, and then this happens and then that happens?'" she says. But she has clearly thought in detail about what made her that way. She calls herself a "third culture kid", using a term first coined by the writer Ruth Hill to describe children raised by expat parents. The lack of belonging that can result is heartrendingly summarised in the title of a guidance document prepared by the US state department, "According to my Passport, I'm Coming Home". But it can also lead to the development of something more positive. "One of the things the research says is that third-culture kids tend to be extremely empathetic, and because they've usually lived in at least one other foreign country, they somehow feel a global alliance, almost ... " Gun tails off, as if embarrassed to make too grand a claim for herself.
The last few hectic days have left her relieved and happy, she says, but completely uncertain as to her future. "I jokingly said to somebody the other day that I'll start making babies, but I don't think I'm ready for that yet," she says. Her only certain plan is to go on holiday with her husband.
Meanwhile, she seems to have no particular burning desire for the government to apologise to her. "I understand that they felt they had to charge me, because obviously I hadn't denied breaking the Official Secrets Act," she says. "But, you know - apologies to me? What's that going to achieve? I've been through what I've been through already. And now I'll just carry on from here."