A police officer accused of punching a pro-hunt demonstrator said he hit out to protect himself and fellow officers, a court has heard.
The pro-hunting protest took place last September
Pc Neil Latteman, 43, said he used police-approved tactics to try to subdue Yorkshire farmer Mark Faulkner, 34, during a Parliament Square protest.
"He was snarling and he was in my face," Pc Latteman told central London's Bow Street Magistrates' Court.
The officer denies one count of common assault during the protest last year.
The officer, who has been in the police for 22 years and is part of the Met territorial support unit, told the court Mr Faulkner was going "berserk".
In his notes, produced hours after the violence on 15 September last year, Pc Latteman wrote: "I threw one punch in his face fearing for my safety."
But witnesses alleged he threw at least two "unprovoked and unnecessary punches" and acted "like a football hooligan", the court was told.
Mr Faulkner, an arable and game farmer who lives near Thirsk, in North Yorkshire, had earlier been accused by the defence of trying to incite the crowd in Parliament Square to break police lines.
Scaffolding clips, fireworks and bottles, some of them filled with urine, were being hurled at the lines of officers by the crowds at the time of the alleged assault.
Mr Faulkner was already under arrest and surrounded by eight or nine officers, the court heard.
But Pc Latteman claimed: "The man was going berserk - that was my impression.
"His feet were kicking out and my impression was that he had thrown a punch at me."
Denied changing notes
Pc Latteman struck out after being hit in the back and feet, but, having watched the video he accepted that Mr Faulkner did not punch him.
He told the court: "At that stage I wanted to stop this man. It was my honest self-belief this guy was a threat to me, the people around me and the other officers. I struck him in the face."
Riel Karmy-Jones, prosecuting, argued that Pc Latteman had struck out in anger "to get" Mr Faulkner back for the violence launched against police that day.
The officer dismissed this as "ridiculous" and denied changing his notes to help justify the alleged assault.
The case continues.