The man I thought was my boyfriend turned out to be a married undercover cop with two children… he went from my bed, to a debrief with his handler, to the bed of one of my activist friends – all on the SAME DAY

Through the course of their relationship, Kate Wilson frequently teased her boyfriend Mark about the amount of time he spent on his phone.

‘He was the original phone addict before it was a thing; always texting,’ she recalls.

‘My friends and I used to take the mickey out of him. He’d tell us it was work stuff.’

That wasn’t entirely a lie, although it wasn’t exactly the whole truth either.

For as Kate now knows from poring over thousands of police documents and files, for the duration of their 16-month romance, Mark Stone – in reality Mark Kennedy, an undercover police officer – was actually working all the time, spying on Kate and her circle and reporting back to his superiors.

‘The first thing he did when he woke and the last thing he did before bed was text his handler,’ Kate says now. ‘They were in contact every few hours.

‘And his handler in turn was in constant contact with a detective chief inspector who was signing off on policy decisions about whether Mark and I would go to Oxford to visit my old college, or whether he should spend the night at my parents’.’

Every bit of their relationship was reported on. Conversations, nights out, family events, Kate’s Valentine’s card, even a trip to Ikea, were all recorded in the flat, emotionless words of a police log: ‘Call from Source [Mark Kennedy] who has left Ikea with a vehicle full of furniture and mattresses on the roof,’ read one entry.

Oblivious at the time to her lover’s real identity, after they split it would be another six years – during which she and Kennedy remained good friends – before, in 2010, Kate learned he was a member of the Metropolitan Police Special Demonstration Squad. This was a covert unit established in 1968 to infiltrate hundreds of protest groups from climate activists to Trade Unions (and, in one instance, a branch of Hedgehog Rescue). He was also married with two children.

Kennedy was arguably the most high-profile cog in a sprawling, state-sanctioned police surveillance operation that lasted four decades. Often deliberately targeting female activists, it involved more than 60 victims, some of whom had children with their undercover lovers and all of whom were devastated on discovering they had unwittingly lived a lie.

In Kate’s case, the emotional fallout led to her failing her medical degree and abandoning her dream to become a doctor.

Several of the women subsequently launched legal action but funding challenges forced them to settle without receiving any real answers. All except Kate, who pursued a further human rights claim which forced police to hand over their files on Kennedy – 5,000 pages in total – and made her the only victim of the ‘Spycop’ scandal, as it became known, to see her own life set out in her former lover’s police reports.

‘I’m not sure it’s possible to convey just how weird it is to sit down and read about your life in this way,’ she says. It’s one reason she’s written a book, called Disclosure, retelling the story of her relationship with ‘Mark Stone’ and chronicling her ten-year legal battle for justice and recognition.

‘It’s my way of trying to make sense of it all,’ she says now.

Aged 47, the convivial and articulate Kate works as an A&E nurse, and lives (she prefers not to say where) with Ben, her partner of seven years, but who is also a longstanding friend and knew ‘Mark Stone’ in the noughties.

‘I don’t think it’s a coincidence,’ she says of the fact the couple share a long history. ‘I think after learning about Mark I would have struggled to form a relationship with someone I hadn’t known before.’

A child in the 1980s, Kate was raised in London by an activist family. ‘I grew up supporting the miners, defending the Greater London Council and singing ‘Free Nelson Mandela’,’ she writes in Disclosure. Those instincts continued into adulthood.

After graduating with a modern history degree from New College, Oxford, Kate briefly settled in Nottingham, where she trained as a translator and joined climate and advocacy groups. She also joined a local activist group – founded, she now knows, by another undercover police officer – where in October 2003, then 25, she found herself sitting next to Mark Stone.

‘I thought he was cute,’ she recalls of that first meeting. ‘He was a little bit different, a bit more of a lad than my male friends.’

Later, Mark told her he had seen her at a previous climate gathering, but hadn’t approached her as she was ‘out of his league’. ‘I was flattered, I suppose,’ she says.

Within days, Kate, known by friends at the time as Katja, was regularly staying over at Mark’s sparsely decorated flat in Sherwood. A few weeks later, he had moved into the shared house where she was living.

The timeline of their relationship is laid out in stark black and white in the time-stamped and dated records he sent to his officers. ‘One of things that struck me when I looked back on those notes is how quickly our relationship developed,’ she says.

Eight years older than her, Kennedy said he was a delivery driver who, like Kate, had grown up in London; in fact, he was raised in Kent. Charming and attentive, he was also cagey about his past, eventually confiding that he’d worked as a courier for a drug trafficking gang in London. ‘It came out in dribs and drabs, like this dark secret he was ‘trusting’ me with,’ she says. ‘He implied that he was running away from that life, and that some pretty dangerous people might want to know where he was.

‘It sounds absurd now, but it’s not something you can exactly check, and of course it provided the perfect reason to draw a veil over things.’

Kennedy claimed his dad had abandoned him and his brother when they were children and that his mother lived in Ireland. ‘In fact, his wife lived in Ireland with his two kids, and his parents were very much together when news broke about him being undercover,’ says Kate. ‘So the broken home thing was rubbish, too.’

Activism and lies aside, theirs was a normal relationship. Kennedy wrote her ‘endearingly awful’ poetry and bought her dinner. ‘We went to the cinema, hung out with friends, just all the usual stuff,’ she says. ‘He would sit and watch football with my parents. He got on really well with my family.’

There were mini-breaks, and discussions about furniture – hence the trip to Ikea, reported in intricate detail. ‘That is one of the few things that made me laugh about those reports,’ she says.

At Christmas 2004, Mark purportedly went to Thailand to undertake a martial arts course, only for the Boxing Day tsunami to strike. ‘I was terrified, checking for texts, a call, an email, watching the news, thinking he might be dead,’ she says. ‘On his return he didn’t want to talk about it.

‘Now I think it’s far more likely he spent that Christmas with his family.’ In any case, within a couple of months, Kate had set her heart on moving to Europe, and told her boyfriend it was over.

‘I liked him a great deal, but I was 26 and I wasn’t thinking long-term,’ she recalls. ‘We called it a day, but he made a whole fuss that I had broken his heart which, knowing what I know now, seems so ridiculous.’ Not in the least because within hours of seeing her off on the ferry (the police log for that day reads: ‘Text from Source, ‘Katja is just pulling out of Dover’ ‘) Kennedy had taken up with Lisa, a friend of Kate’s and a fellow activist who would, six years later, discover Mark’s true identity when she found a hidden mobile phone and a passport with his real name.

‘The logs show that Mark went straight from my bed to a debrief with his handler, to her bed in Leeds. The same day. He didn’t miss a beat,’ Kate says.

This knowledge lay in the future, however. Kate moved first to Spain then Germany and, despite their split, Kennedy was one of her most regular visitors. ‘He was one of the few people I was in regular contact with from the UK. I considered him a good friend.

‘And I found it quite difficult reading the files later because he would visit and write these terribly affectionate emails, and then he’d be moaning to his handler about how awful I was.’

Indeed, Kate, by now studying for a medical degree in Barcelona, spent a weekend with Kennedy just two months before receiving a phone call out of the blue from an activist friend in 2010 in which she learned the devastating news that her former lover was an undercover police officer.

‘It’s like a motorway pile-up in slow motion where one car brakes, then another and another. It came crashing in waves,’ Kate says of initially learning that Mark Stone did not exist. ‘I had no frame of reference for it. How can you?’

She returned to the UK almost immediately, fuelled by an urgent need to be among people who’d been there during their relationship. There was a further gut-punch to come when she discovered her former lover had been married with two children. ‘I wouldn’t have had a relationship with him if I’d known he was an undercover officer, but I also wouldn’t have had a relationship with him if I’d known he was married,’ she says. ‘It was a double betrayal.’

As the months wore on, Kate also discovered she was the first of 11 women ‘Mark Stone’ had slept with during his years undercover. ‘Those are the confirmed ones, anyway,’ she says.

Amid the bewildering aftermath of betrayal and grief, one of the many questions that gripped Kate was whether any of what they had shared was real – a question Kennedy helped to answer when, after hiring publicist Max Clifford, he gave an interview in which he dismissed their romance as an ‘on/off’ thing that had never really constituted a relationship.

‘It was horrific to read, but I guess it quickly ripped the plaster off,’ she says now. ‘There was no ambiguity. It helped me understand quite quickly that none of it was real, not for him, and that, as he wasn’t remotely the man I thought he was, my feelings can’t have been real either.’

This did not, though, lessen her feelings of grief and confusion. ‘It felt as if one of my best friends had died, and I missed him terribly. All I wanted was to talk to him and tell him about this insane thing that had happened – except he was the insane thing,’ she says.

She was plagued with insomnia and night sweats and, on occasions, went into something akin to a fugue state. Unable to concentrate, she failed her vital medical exams by one mark and had to leave the course.

It’s this devastating career failure that ultimately enabled her to take her fight to the Investigatory Powers Tribunal (IPT), which investigates complaints about the alleged conduct of public bodies.

Along with seven other women, in 2011 she joined a civil action against the Met led by renowned feminist lawyer Harriet Wistrich, only for her peers to be forced to settle four years later or face bankruptcy. But because of the quantifiable loss of her medical career, Kate was the only one advised that she didn’t have to.

‘Part of me wanted them to say differently,’ she says. ‘There had been so many years of bullying and obfuscation and delaying tactics from the police and it was exhausting. But it was about getting answers, and I knew I had a duty to go on. Sadly, having a lucrative career destroyed is worth a lot of money, unlike the emotional distress of the women who missed out on having children because they spent their prime childbearing years with these men, or those who had children with men who didn’t exist.’

Her battle ended in victory in 2021 when the ITP ruled she had been subjected to an ‘unlawful and sexist’ operation and awarded her £229,000 compensation.

By then, she had spent years poring over her files, seeing her life with Kennedy laid bare – and finding the answer to one question at least. ‘For years, I wondered whether I was a target, a tool, or a perk of the job,’ she says. ‘What these documents made clear is that I was never named as a target while we were together.’

Curiously though, she was identified as a target after they split and she moved abroad. She doesn’t know why. Perhaps she’ll learn more next year, when Kennedy is due to give evidence at the ongoing public inquiry – now in its eleventh year – into undercover policing.

Kate hopes he will tell the truth although, beyond that, has few feelings towards the man who once shared her bed. The last she heard of him, Kennedy had left the police and, after initially trying to work as a private investigator, was selling hot tubs to hotels and holiday parks.

‘It’s not really the James Bond movie ending is it?’ she asks. ‘And one of the things that struck me was that, yes, we have this sinister secret state operation, but it’s also made up of people who might otherwise be furniture salesmen.

‘And it underlines just how dangerous it is to take these men, give them a mask and a secret identity and cut them off from the kind of social controls that make people act decently. There has to be some kind of public oversight.’

It is something Kate is determined to fight for, no matter how long it takes. ‘And that’s the funny thing really. This relationship, which at the time was perfectly ordinary, has ended up becoming this life-defining thing.’ 

• DISCLOSURE: Unravelling The Spycops Files by Kate Wilson (£20, Weidenfeld & Nicolson) is out now. Buy it at the Mail Bookshop for £18