An assault on a drunken off-duty soldier by a special constable was "violent, excessive and unjustified", the police watchdog said today.
Peter Lightfoot, 40 was today found guilty by a jury of assaulting Lance Corporal Mark Aspinall after they viewed CCTV footage of him pushing his head into the ground and striking him with a police helmet.
The attack on the soldier, who served in Afghanistan and Iraq, happened in the early hours of July 27, 2008 outside a bar in Wigan, Greater Manchester.
Two other officers involved in the incident, Sergeant Stephen Russell, 34, and Pc Richard Kelsall, 29, were cleared of assault and perverting the course of justice.
L/Cpl Aspinall was himself initially charged and convicted on two counts of attacking the police officers by Wigan magistrates who did not view the CCTV.
He later won an appeal to have the verdict quashed at Liverpool Crown Court last November, as the judge cited concerns about the actions of the officers.
Police were called to the Walkabout bar in the town centre after it was claimed the soldier had caused a disturbance as he shouted racial abuse at door staff when he was thrown out.
The three officers then attempted to arrest the soldier in the middle of the road.
The trial at Manchester Minshull Street Crown Court also heard evidence that L/Cpl Aspinall allegedly obstructed paramedics who attempted to treat a woman who had collapsed.
Lightfoot was also convicted of one count of perjury which concerned evidence he gave at Liverpool Crown Court about the incident with L/Cpl Aspinall.
The charge of perverting the course of justice alleged the two other officers provided false accounts in their witness statements about the circumstances surrounding the arrest.
The charges were brought following an investigation led by the Independent Police Complaints Commission (IPCC).
Following the verdicts, IPCC Commissioner Ms Naseem Malik said: "It is clear from the evidence that Mr Aspinall was drunk, aggressive and causing a nuisance. He was exhibiting the kind of behaviour that police officers have the unfortunate duty to deal with on a regular basis.
"That is why officers are trained to deal with such individuals in a professional manner. However in this incident Special Constable Lightfoot's training would appear to have been replaced by a red mist. His actions were violent, excessive and unjustified.
"I am grateful to Greater Manchester Police and our investigators for the thorough and professional work they have done in examining this matter. I have noted the jury's decision in relation to the other officers and we respect that.
"The IPCC and Greater Manchester Police must still consider whether it is appropriate for any of the officers to be subject to misconduct action."
Lightfoot will be sentenced on September 1.