A joint investigation by BBC Newsnight and the Guardian has uncovered another case of uncover police officers engaging in relationships with people they were monitoring. The man, who went by the name Carlo Neri, was said to have proposed to a woman and lived with her for two years, while he had another wife and child.
Speaking to the investigation, the woman said she had undergone "psychological torture". The Met police would not confirm the story.
The woman was linked to the Socialist Party, which was thought to have been targeted by a long-term infiltration. The relationship was said to have occurred between 2002-2004, with Neri proposing to her in 2003.
Neri is said to have invented reasons to leave the house he and the woman shared in London to spend time with his other family in Cornwall – at one point he showed the woman a picture on his phone and told her it was a son from a previous marriage with whom he wanted to reconnect.
"He was probably away from home for four or five nights every fortnight, and that would be due to work trips," the woman told the investigation ""As far as I was concerned, I was going to spend my life with this man, and his life was my life."
Neri allegedly pretended to be a locksmith and helped friends of the woman in the Socialist Party when he could. "With hindsight there's a different perspective really because there's a huge amount of people's locks that someone had access to," the woman said.
The relationship became difficult at the end of 2003 when Neri said that his father was ill in Italy and told her that his father had sexually abused a female relative. The woman says that she now thinks this was part of a plan to end the relationship.
The new allegations come after the Met police was forced to apologise last year after similar cases were discovered. They called the relationships "abusive, deceitful, manipulative and wrong" and agreed to pay substantial compensation.