A former undercover police officer has been sacked from the Met after having a sexual relationship with a woman in a campaign group he was targeting.
Det Con Jim Boyling, who worked for the Special Demonstrations Squad (SDS), was found guilty of gross misconduct.
Using the name Sutton he infiltrated the campaign group Reclaim The Streets and had relationships with three women.
Det Con Boyling has accused Scotland Yard of having "selective amnesia" about what he had previously told them.
It is the first time such a finding has been made in relation to an undercover officer.
The Met said his actions had been "unacceptable".
Posing as a fellow anti-roads protester, the officer had relationships with women in the group.
When the third woman, known only as Rosa for legal reasons, tracked him down in 2001 they resumed the relationship and the officer subsequently revealed his true identity.
They married and had two children but she left him six years later, accusing the officer of not only tricking her into the first relationship, but psychologically manipulating her into getting back together and forming a family.
During the week-long disciplinary hearing, a panel heard allegations the officer had begun a sexual relationship with Rosa "without authorisation and without a policing purpose".
The panel ruled this amounted to gross misconduct.
It further ruled the officer had failed to disclose the relationship to his superiors and he broke strict police rules by admitting to Rosa he was an undercover officer.
"Undercover policing is an important and lawful tactic, but it must never be abused," Deputy Assistant Commissioner Richard Martin said.
Det Con Boyling, who was an officer for 30 years, said: "The disciplinary charge from the Met specifies that I had a relationship which constituted misconduct because it was 'without a police purpose'.
"The position of the Met appears to be that a relationship entered into as an operational tactic is acceptable, but a genuine one resulting in marriage and children constitutes misconduct."
He said he used his real name and registered his occupation as a police officer on the marriage certificate and both birth certificates, and that Rosa knew he had worked undercover. He also made a written declaration of his marriage to the Met's vetting unit.
"The Met does a good line in selective amnesia, as indeed they do in selective disclosure," he added.
Det Con Boyling said he did not contest the Met disciplinary hearing because he could not afford to stay in London during the proceedings, and did not wish to drag former colleagues and his ex-wife through the process.
However, he said he would give evidence to the public inquiry into undercover policing.
The Metropolitan Police has already made an unreserved apology to Rosa and 11 other women who had relationships with undercover officers and has paid out substantial sums in settlements to the women.