A 32-year-old man who says he suffered a depressive illness as a result of discovering that his father was not a political activist but an undercover policeman has won the latest round of a High Court compensation battle with the Metropolitan Police.
The man sued Metropolitan Police Commissioner Cressida Dick - arguing that the force head was responsible for his father and the officers supervising him.
But lawyers representing the force asked a judge to dismiss the man's claim entirely - arguing that there were "no reasonable grounds" for launching it.
Mr Justice Nicol on Monday refused to take such a step. The judge said the man might win compensation if he demonstrated that supervising officers had failed to provide a "duty of care" they owed him
Mr Justice Nicol, who analysed the issue at a High Court hearing in London in October, has not named the man in a written ruling.
But he said the man's father was an undercover policeman named Bob Lambert who used the pseudonym "Bob Robinson" when working undercover.
He said the man's mother had been a political activist.
Mr Lambert pretended to share the woman's political views during the mid-1980s and "formed a liaison" which resulted in the man's birth.
He "purported to fulfil" a "father's role" until 1988 when he "pretended that he had to leave to avoid prosecution", said Mr Justice Nicol.
His son lost contact with him until his role as an undercover policeman was revealed about five years ago.
Justice Nicol referred to the man as "TBS" in his ruling and to the man's mother as "Jacqui".
He said the man's mother launched a separate damages claim four years ago and received £425,000 following a settlement.
"The claimant was born in September 1985," said Mr Justice Nicol in his ruling.
"His mother was a political activist who is referred to as 'Jacqui'. His father was Bob Lambert.
"Lambert was an undercover police officer who, using the pseudonym Bob Robinson, pretended to share Jacqui's political views and formed a relationship with her which resulted in the claimant's birth."
Mr Justice Nicol added: "The claimant seeks compensation for, among other things, the Adjustment Disorder with Depressed Mood which he says he suffered as a result of finding out that his father was not a political activist but a police officer, from Lambert purporting to assume a father's role under a false identity and from Lambert abandoning his parental role towards him and relying upon a false explanation."
The man has alleged misfeasance in public office and negligence.
He says the commissioner had a responsibility for Mr Lambert and supervising officers.
The man says officers supervising Lambert were at fault for deploying him as they did and for allowing his role to continue after he had fathered a child.