I spent five blissful years with my boyfriend and longed to start a family together… until the day he suddenly vanished. Then, I made a terrifying discovery that changed everything: ALISON SMITH

During their five-year relationship, Alison Smith would sometimes jokingly call her boyfriend ‘Sarge’.

‘He was very motivating,’ she smiles. ‘The kind of guy who would get you walking through deep snow in minus-ten degrees. It was one of the things I loved about him.’

But then, there seemed to be a lot to love about Mark Cassidy, a handsome, affable carpenter from Birkenhead with a ready sense of humour. Alison’s family liked him, as did her friends.

There was just one problem. In reality, Mark Cassidy – the man who shared Alison’s life, and bed, for five years – was someone else entirely.

In fact, his name was Mark Jenner, and he was a married father, undercover police officer and a real-life sergeant in the Met Police’s Special Demonstration Squad (SDS) set up to infiltrate protest groups, including the one Alison belonged to in East London.

In other words, Mark was a spy, part of a sprawling police operation often deliberately targeting female activists in what Alison witheringly calls a ‘state-sponsored lie’ based on ‘psychological violence’. ‘This is not simply about living with a conman,’ says Alison, about the gradual realisation that her lover was not who he claimed to be. ‘This is about being manipulated over the course of years with the full backing of the state.

‘Discovering this had the most enormous effect on my wellbeing. It was not just that my entire relationship had been a lie, but that I felt I’d uncovered something I wasn’t supposed to uncover – and that felt incredibly frightening.’

Alison’s story is one of five featured in ITV’s mesmerising new three-part documentary, The Undercover Police Scandal: Love And Lies Exposed, which airs next week.

Some of those featured are talking publicly for the first time about their involvement in a four-decade-long scandal thought to have involved more than 60 female victims, some of whom had children with their undercover lovers. ‘The similarities between so many of the stories are extraordinary – right down to the break-up letters they wrote,’ says Alison. ‘The legacy is the same, too: betrayal and damage.’

Now 59, Alison is an articulate and charismatic married mother of two. It is not hard to picture her as the passionate and idealistic young woman who crossed paths with ‘Mark Cassidy’ in the mid-1990s.

Raised in a Left-leaning family in north London, Alison was working as a teacher at an inner-city secondary school and was active in her trade union and ‘anti-fascist’ politics when she met Cassidy.

She had also joined a community-based group that campaigned on social justice issues, including anti-police corruption. ‘It was a pretty broad church, made up of people from all walks of life; and unlike so much of the Left, they didn’t feel like middle-class people playing at politics, but quite serious people trying to bring about real change,’ she recalls.

It was here that she first encountered Cassidy who, clad in a lumberjack shirt and sporting a stringy pony tail, seemed perfectly at home. The two hit it off instantly, their initial friendship quickly blossoming into romance and, within a year, Mark had moved into Alison’s flat from the bedsit that had served as his ‘home’ until then.

‘From February 1996 until April 2000 we absolutely lived together and spent pretty much all of our time together,’ she says. ‘Later, after everything happened, I said to some close friends: “He was here all the time. I haven’t imagined that, have I?” But he really was.’

Mark went to meetings with Alison, although her group was non-violent and she has no idea what activity he was reporting back on.

To all intents and purposes, theirs was an ordinary loving relationship.

‘Our politics were on the radical side, but our relationship was very conventional,’ she says. ‘I was a teacher; I did my marking in the evening. We watched EastEnders and Coronation Street, and often went to my mum’s house for Friday night dinner. We saw friends, or people came over. We went on walking holidays. He got on with my family, including my nephews and nieces.’

Like Alison, Cassidy also got up and went to work every day, supposedly fitting kitchens. ‘I think he was actually going home to his wife, and when he told his family he was at work, he was coming to me. Which is true – because I was his work.’

Certainly, at the time nothing about her partner stood out to Alison as troublesome. Yes, Mark had little family to speak of, but he said his dad had been killed in a car crash, and he was, as he told her, ‘basically estranged’ from his mum.

There was a grandfather, but Alison never met him; on the one occasion they were supposedly going to visit, Mark turned his van round half way there claiming his ‘forgetful’ grandfather had mixed up the date.

With the illumination of hindsight, however, some moments now stand out.

‘In December 1996 my ex-partner died. I was devastated by that news, but so was Mark, which was strange,’ Alison says. ‘When I asked him why he was so upset, he said it was because he’d always thought that if we split up, I’d get back with him.

‘It was such an odd thing to say, but now I think he obviously knew we were going to split up and that thought made him feel better.’

Odder still was the occasion when, searching through Mark’s jacket pocket for a leaflet, Alison came across a credit card in the name of M. Jenner. ‘When I confronted him, he told me that in a stupid moment he’d bought it from a bloke in a pub and used it to buy petrol. And I completely believed him,’ she says.

Nonetheless, she made a note of the name, and put it in a drawer in her dressing table. ‘I’m sure that psychologists could do a lot to unpick that,’ she says wryly.

It was only when, around four years in, Alison’s thoughts turned to children that the relationship hit a bump in the road: Mark was reluctant, leading Alison to suggest counselling. ‘I remember dragging him along the street, he really didn’t want to go,’ she says. ‘But I said we had to resolve this.’

They were still mid-counselling when Alison returned from work one day in April 2000 to a note from Mark saying he had left because the pressure had become too much. ‘We want different things,’ it read. ‘I can’t cope…When I said I loved you, I meant it, but I can’t do it.’

He claimed he was going to Germany to look for work, and left no forwarding address. In fact, he was back working just a few miles down the road, at Scotland Yard.

‘I was hysterical,’ Alison says. ‘This was my relationship; we effectively were like man and wife. So my starting point wasn’t anything to do with conspiracy, I just wanted to find him. This is not how people break up, certainly not after five years.’

Yet quickly, the oddities started to pile up: the address of Mark’s grandfather had been violently scribbled out of the address book to the point of complete illegibility, while the scrap of paper on which Alison had once scribbled the name M. Jenner had also vanished.

Puzzlingly, his employer Terry – with whom Mark claimed to have a family connection, once buying a Teletubbies jigsaw for his grandchildren – didn’t seem to know much about him.

‘When I rang his workplace, the woman who answered the phone didn’t seem to really know who Mark was, and Terry just seemed a bit baffled I had got in touch. I now think that Teletubbies jigsaw was for his own children.’

There were many other things that did not add up. When Alison rang the DVLA to enquire after Mark’s van, she was told there had been ‘a lot of enquiries about that vehicle’. At the family records centre, meanwhile, she found out that there was no trace of his father’s death.

‘At that point I thought: “So if he’s lied about that, then what else has he lied about?”’

Yet only when she received a message on her answerphone for Mark from another campaign group did more chilling thoughts start to fall into place.

‘The message was asking him to ring about a meeting, so I phoned back to tell them he had gone,’ she recalls. ‘Whoever answered said we needed to meet up as they had a few questions, which I thought was strange, but when we did meet he said: “We just needed to check he’s not a spook.”

‘It was the first time I had heard that word. The man asked me a few questions, like how Mark paid for things, and then said it felt like he was just an ordinary bloke who’d done a runner.

‘But when I came out of that meeting, the more I thought about it, the more convinced I was that he was an agent of the state.’

The realisation ultimately triggered a form of breakdown. ‘I was high-functioning – I still functioned well at work. But in my personal life and in my private life, I was extremely disturbed and extremely paranoid, and I can only describe those first few years after Mark left as very, very dark,’ she says.

‘I’ve got notebooks of when I was up at 3am, looking out the window, logging car numberplates. I was convinced I was being watched, that there was a hidden camera in the bedroom, that sort of thing. That was where my mind was at.’

Aside from her mum and one friend, however, her convictions were not shared by anyone else.

‘My stepfather believed he was a bigamist. My brother just thought I was constructing this James Bond fantasy because I couldn’t face the truth that he’d left me,’ says Alison. ‘Basically I came across as a lunatic.’

Only when, in 2003, she met her now husband was she able to ‘get on with my life’.

‘I don’t think it’s a coincidence that after what had happened, I married someone whose cousin had been in my class at school,’ she says. ‘It meant I knew he was exactly who he said he was. So I had my children, life went on. I wouldn’t say it was completely behind me, there was still an itch, but I wasn’t going to let it consume me.’

Then, in 2010, rumours started to circulate of an undercover police operation infiltrating Left-wing groups.

Not long after, they were shockingly confirmed – with the unmasking of yet another Mark, this one Mark Kennedy, an undercover officer who had been spying on climate change activists. The person who discovered Mark Kennedy’s true identity was his long-term girlfriend ‘Lisa’.

The revelation set in motion a chain of events that led to a 2014 public inquiry into what became known as the ‘Spycops’ scandal, as well as a civil case for damages from the Met Police by a group of victims, Alison among them.

The legal action ended in a fulsome public apology from the then Assistant Commissioner Martin Hewitt and substantial damages paid to each of the claimants.

Throughout, however, the Met Police continued to ‘neither confirm nor deny’ Alison’s requests regarding her former partner’s background. Then, in 2015, a statement by Peter Francis, a former undercover officer-turned-whistleblower, was read to a public meeting held in Parliament in which he stated that Cassidy was ‘a fellow undercover SDS police officer’ whose real name was Mark Jenner. The Met finally formally confirmed Jenner’s true identity in 2018.

By then, Alison had already learned from a source that he was married with children.

‘It wasn’t surprising,’ she says of the news. ‘I knew the other women’s stories, so it was always likely.’ Overall, all of it was less devastating after ‘validation and affirmation after years of madness and questioning your own judgment’.

But did he ever have real feelings for her? Alison says: ‘There was genuine lust and attraction, but the idea they were genuine feelings implies there’s something honourable about it. I don’t believe these men have the capacity to love in that way.’

The legal battle, meanwhile, sprang from a determination to ensure that other women would not be subjected to what she and other victims had endured.

‘The only way we would ensure that is to make it illegal – and we’re still fighting for it,’ says Alison. ‘Police guidelines now state that undercover operatives shouldn’t have sex with members of the public. That is a massive step in the right direction, but it is still not against the law.’

She is angered, too, by the ongoing refusal by the Crown Prosecution Service to prosecute any of the officers for sexual offences. ‘They say the relationships they had were based on genuine feelings and that they were consensual,’ she says. ‘Our counter to that is that we didn’t have informed consent. We were being deceived.

‘There are things that shouldn’t happen. And a police officer having sex with a member of the public using an undercover identity that’s been funded and paid for by taxpayers is one of them.’

The Undercover Police Scandal: Love And Lies Exposed starts on Thursday, March 6 at 9pm on ITV1, ITVX and STV Player.