An undercover police officer has publicly confessed to deceiving a woman into a five-year relationship while spying on left-wing and anti-racist groups in London during the 1990s. Mark Jenner, who used the fake identity Mark Cassidy, told the Undercover Policing Inquiry that his actions were "extremely cruel" and turbo-charged his covert operation.
A Life Built on Lies
Jenner, operating under the alias Mark Cassidy, infiltrated activist circles in Hackney, east London, between 1995 and 2000. During this deployment, he began a relationship with a woman known to the inquiry as Alison. For four years, they lived together as a couple, with Jenner becoming deeply embedded in her life and family, attending weddings, funerals, and going on holidays abroad.
All the while, he concealed his true identity as a member of the Metropolitan Police's Special Demonstration Squad (SDS). He also hid the fact that he was married with children, betraying both his wife and Alison. He admitted his treatment of his now ex-wife was a "gross betrayal" and "appalling".
'Perfect' Cover and 'Open Secret'
Jenner told the inquiry that the relationship provided the "perfect" opportunity to present himself as a credible, rounded individual, which helped him gain the trust of the activists he was spying on. He admitted he was "not interested in avoiding a deceitful sexual relationship".
Shockingly, he revealed that his relationship with Alison was an "open secret" within the SDS, known to a number of his managers and colleagues. They did nothing to stop it, merely warning him to be "very careful", with one officer even joking about the situation.
The Human Cost of Deception
The inquiry heard how Alison wanted to have children with Jenner. He admitted to deliberately stringing her along, agreeing to the idea but saying he wanted to wait. When asked if he was "wasting her fertile years", he replied: "That is the reality of it, Yes."
He conceded that he never considered whether Alison would have consented to a relationship if she had known his true identity. In 2000, he abruptly vanished from her life, feigning severe depression. It took Alison over a decade of research to discover he had been an undercover police officer.
Jenner was later given a commendation by his superiors for his covert work. The ongoing inquiry is examining how undercover officers spied on tens of thousands of activists between 1968 and at least 2010, with the formation of sexual relationships using fake identities being a central issue under scrutiny.
