It wasn't that she was naive. Katharine Gun knew exactly the sort of work she was employed to do; two years into a job at GCHQ as a Mandarin "analyst" and "translator", it's hard not to. It's just, back then, she didn't realise quite what her employer could be capable of.
The morning of Friday the 31st of January, 2003 started out just like any other. "I got into the office, turned on my computer and looked through my emails," says Katharine, more than 16 years later. "And there in my inbox was was this email from [the US] National Security Agency, which in and of itself was quite out of the ordinary."
Katharine read the content carefully, and immediately felt sick to her stomach: it was a classified directive from the American authorities asking the British to spy on six UN Security Council members. Any intelligence gathered would be used as leverage to coerce those nations into sanctioning a war in Iraq.
Right away, Katharine knew the significance of this message. She'd been reading up on the preparations being made for a US-led invasion and wasn't convinced by the arguments; images of the first Gulf War she'd seen in her teenage years had forever been seared onto her mind. Now, she was being asked to help get a new war authorised by finding material for the Americans to blackmail and bribe the international community. This information could be huge for the growing anti-war effort – Katharine thought it might even help put an end to talk of invasion once and for all.
"This was crossing a red line for me," she says. "And I immediately decided the public should know the lengths the Americans were going to in order to secure legitimacy for this war. I could tell this email was pretty explosive."
Raising the issue with a manager briefly crossed Katharine's mind, but time was limited – the threat of war was escalating fast – and ultimately this operation had already been signed off by British top brass. Katharine feared she'd be fobbed off and then put under surveillance should she report it, so instead she kept silent and headed home for the weekend. The following Monday, she walked out of work, a printed copy of the email folded up and hidden in her handbag.
That night, Katharine posted the letter to a contact whose identity she continues to withhold. From there, it made its way into the hands of Yvonne Ridley, a well-known anti-war activist. The next morning, Katharine returned to the office as normal and got on with her work, trying as best as she could to not think about it.
Two weeks later, on the 15th of February, 2003, a million people took to the streets of London to protest the prospect of Britain joining the war in Iraq. Katharine was amongst them. "Public opinion was just so obviously against the invasion that I thought it wouldn't happen," she recalls. "Tony Blair was so obsessed with popularity ratings, I thought that would really affect him."
We're sitting together in a quiet room at the headquarters of human rights organisation Liberty, just around the corner from the streets through which she'd been marching. "It felt like the protests were what would stop the war," she says. "It got to the stage where I was certain the email I'd leaked wouldn't be needed, that it would never surface."
A few weeks passed and no story appeared. Maybe reporters decided it was a fake, Katharine thought; maybe she'd just entirely misjudged its significance. Life carried on. And then, one morning, Katharine popped to her local shop to pick up the paper, as she did every Sunday, and there, on the front page of The Observer, was the email she'd leaked. Now the public knew.
"I immediately felt like I was in danger," she says, describing her internal panic, the desperation to look calm and to not draw any attention to herself. "As soon as I got home I sat with my husband, who was still in bed. I couldn't control myself – I was a total state, crying and trembling."
Katharine had assumed a journalist would use the letter as a springboard for their own wider investigation. Instead, the memo had been produced on the front page in its entirety. This presented a problem. Only a select number of people had received the communication, and GCHQ were going to want to know who'd blown the whistle.
The following Monday morning, Katharine could immediately tell there was an atmosphere in the office. Everyone was a suspect, as one by one colleagues were called into interviews with GCHQ's internal security team. On Tuesday, it was her turn to be questioned. To this day, she has no idea how convincing she was during her interrogation – but really, it doesn't matter: on the Wednesday, she marched right up to her manager. "I need to have a word with you," she gulped. "It was me."
It took two hours for the cops from special branch to reach GCHQ in Cheltenham. In that time, Katharine was interviewed again, and then escorted to the canteen. When she arrived, escorted by security, all her colleagues knew too. Katharine spent that night in a cell underneath the local police station. With no plan and no contacts, a duty solicitor – who was well out of her depth – was called.
Katharine's house was searched before she was sat down to be interviewed the following morning. "The officer shook my hand once I was bailed and released," Katharine recalls. "He said, 'It was a pleasure to meet you, Ms. Gunn, I'm just sorry it was under these circumstances.'"
Things moved slowly from then. A union rep got in touch to offer support, and once news broke that an unnamed woman had been arrested for the leak the story caught the attention of the organisation whose offices we're sitting in. Soon, Katharine was in touch with John Wadham, then Director of Liberty. For eight months she was bailed and bailed again, repeatedly. "We just kept waiting in this state of limbo, a constant cloud over my head," she explains. "At the back of my mind, the question remained: 'What are they going to do to me?'"
Meanwhile, the war in Iraq had already started. On the night of the 19th of March, 2003, the bombs began to fall. During that period of purgatory, I ask, did she regret it all? Her life had been turned upside down, and for what? "Yeah, I suppose so," she says. "But there are things you have to do not for the result but for the principle, because they are right."
And then, in November, came the call from her lawyer. The Crown Prosecution Service was about to charge her. It wasn't the news Katharine had been preparing for. She'd be tried at the High Court; the press and the public would know this whistleblower's name. She headed up to Yorkshire and went into hiding, as a media circus descended onto Cheltenham to find her.
"Once that initial flurry died down," says Katharine, "I returned to London to meet with the team from Liberty and my lawyer, Ben Emmerson. We came up with an idea for a defence – that I acted out of necessity – but generally there isn't one for breaching the Official Secrets Act."
There was also the question of the plea: would she admit to being guilty or argue her innocence? The advice was that, by accepting what she'd done was illegal, the jail time might end up reduced. "The problem was that I just didn't feel guilty," she tells me. "I'd have a criminal record for doing what was right." And so it was decided: on the stand she'd state her innocence and hope for the best.
On the 25th of February, 2004, Katharine arrived at the Old Bailey for her trial. Within half an hour, the prosecution had decided to drop its case, for reasons that to this day remain mysterious. It has been suggested that the government was desperate to ensure that documents containing advice about the legality of the war – which the defence had requested – would not be made public. Katharine wonders whether the powers that be just didn't want an ex-GCHQ employee – with all she knew – to be cross-examined on the stand.
It's taken a long time for Katharine to feel comfortable talking about everything that happened. That level of pressure, stress and attention took its toll. "Even thinking about it all would cause me anxiety," she says, "but now I am ready." Today, she lives in Turkey, with her husband and their child. This month, a new film – Official Secrets, in which she's played by Keira Knightly – will be released, telling her story.
"The world is moving in a completely fascist, corporate direction," she tells me, when I ask if – thinking back – she'd do it all again. "It worries me, it should worry us all. And what we are seeing is a movement of people who are trying to stop it. Whistleblowing on wrongdoing is part of that fightback. It isn't a crime, it's a responsibility."
Official Secrets is released in cinemas on the 18th of October, 2019.
This article originally appeared on VICE UK.