Moment woman realised partner of five years was actually an undercover cop with a completely different life

A woman has opened up about the shocking moment her world came crashing down as she realised her partner was an undercover police officer, with the horrifying case being told in a new ITV documentary.

Alison was just one of many women that were subjects of a mass surveillance of left-wing activists in the UK between 1960 and 2011.

The cases have now been compiled into an ITV documentary titled The Undercover Police Scandal: Love and Lies Exposed.

At least 60 women were targeted by the undercover police unit, and Alison went on This Morning to tell her own story.

The documentary, which has been released this week, follows these shocking experiences, as Alison revealed on the show that she was with the man for five years before he left her.

It turns out he was among a number of officers that were part of a division called the Met's Special Demonstration Squad.

Alison met a man named Mark Cassidy in 1995 at one of her group meetings in Hackney, who claimed to be a joiner from Birkenhead.

She recalled that he was a part of her life, even meeting members of her family when they were together.

Of course, it was all a ruse, and he was just gathering information on the activist group she was part of.

The entire ordeal has been dubbed the 'spycops scandal', and became the subject of an £88 million public inquiry, according to ITV.

Alison recalled the times where she sensed that something was not right with her 'partner', and told the story of how he left her.

She was tricked by her 'boyfriend' of five years (ITV)

After finding a credit card in someone else's name in his jacket pocket, she thought nothing of it, cutting it up after he claimed he had stolen it.

But one day he vanished out of her life, leaving her with nothing but a note on the table.

Alison, a teacher at the time, came home to the message that Mark had left her, commenting that that's 'not how you end a five-year relationship'.

"I needed to make sense of that and to do that I needed to speak to people who knew him - that took me to looking in my address book for his grandfather's number, that was really hard scribbled out," she explained, revealing that she was meant to meet him, though it was cancelled last minute.

She ultimately did her own detective work, uncovering that 'Mark' was an undercover cop, and claimed that she knows 'a lot more' about him as a person 25 years on from the relationship's end.

Alison moved on with her life in the end (ITV)

Alison also claimed on the show that the division was run through taxpayers' money, and that she wasn't the only woman that was targeted by the officers.

She explained: "He was part of a machine if you like, he had managers, there was a back office, there was a manual that told them how to manage this deceit."

The hosts pointed out that she was 'lucky' to move on with her life, having planned to have children with Mark at first, but hinted at the fact that she was now happy and has accepted what happened.

The Undercover Police Scandal: Love and Lies Exposed is available to watch now.