A pro-hunt demonstrator was punched by a policeman despite him being held by other officers, a court has heard.
The pro-hunting protest took place last September
Met Pc Neil Latteman, 43, threw two, possibly three, "unprovoked punches" last September at Mark Faulkner, Bow Street Magistrates' Court heard.
The North Yorkshire farmer was accused by the defence of trying to incite the crowd in Parliament Square to break police lines.
Pc Latteman denies one count common assault during the protest last year.
In the case brought by the Independent Police Complaints Commission (IPCC), the court heard Pc Latteman allegedly lunged at least 8ft towards Mr Faulkner in an action described by one eyewitness as "like a football hooligan".
Mr Faulkner, 34, an arable and game farmer, from near Thirsk, joined the protest on 15 September at about 1530 BST with his nephew and an employee.
The prosecution said the crowds began to surge forward when they heard MPs were going to vote on the Hunting With Dogs Bill.
At this time Mr Faulkner, who was at the front of the protest, was hit twice by a police officer with a baton and recalls nothing until several minutes after the alleged assault by Pc Latteman, The Chief Magistrate of England and Wales, Timothy Workman heard.
Riel Karmy-Jones, for the prosecution, said: "Shortly after Mr Faulkner was extracted from the crowd and police officers had him pushed against a van.
"His next recollection is being between two police vans in handcuffs."
But footage filmed for private investigators and later studied by the IPCC allegedly shows Mr Faulkner being struck by Pc Latteman after he had been pulled from the crowd.
Mr Faulkner suffered several injuries, including a black left eye, and was left needing hospital treatment, the court heard.
Michael Shaw, for the defence, put to Mr Faulkner during cross examination, that he encouraged crowds to surge forward during the protests to get to the Houses of Parliament, and that he was being aggressive to the officers holding him.
He denied both accusations.
The case continues.