A stop and search adviser to the Mayor of London headbutted a police officer when he intervened as his friend was arrested.
Kenneth Hinds, 59, who has also worked with the Metropolitan Police, stepped in as officers detained Jamal Thomas Edwards on suspicion of drugs offences.
A court heard his friend was calm during the arrest until Hinds questioned the officers about why he was being detained.
Thomas Edwards then began shouting a phone number to Hinds and “resisting” arrest, Highbury Corner Magistrates Court was told, and Hinds assaulted an officer in the struggle which followed.
Hinds, from Haringey, north London, was convicted of assault on a police officer and obstructing police after a judge said his actions “could have gone horribly wrong for everyone.”
District Judge Susan Williams said he “acted out of the best of motives” but got “carried away” when he assaulted PC Richard Cousins as the officer tried to move him away.
The officers who arrested Thomas Edwards had also detained another man moments earlier after he was found to have a “combat knife” but the judge agreed Hinds did not know that.
Handing him a 12-month conditional discharge, she said: “You made the situation considerably worse. Fortunately nobody was injured in the process. It could have turned horribly wrong for everyone.”
Hinds was also ordered to pay £670 in costs over the incident on April 16 but his solicitor, Simon Natas, said they will appeal the conviction.
Judge Williams said: “I think Mr Hinds acted out of the best of motives in the worst possible way.
“That I think is the effect of all of this. Unfortunately, he didn’t know exactly what was going on.
“If he had known, I strongly suspect he would have behaved in a very different way.
“Unfortunately, when things happen quickly there is not the time or opportunity to give the explanation he felt was merited at the time and to which he mistakenly felt he was entitled.”
She added: “This was a difficult situation.
“Sometimes it seems to me the best thing to do is when you are asked to stay back and stay out of it is to stay back and stay out of it.
His trial heard an officer had told Hinds that Thomas Edwards was “alright” as he was being detained.
But as he continued to ask why they were making the arrest, his friend became more agitated and began shouting a phone number which Hinds was “determined” to note down.
Police feared if Hinds made a call it could lead to evidence being destroyed.
Judge Williams said: “By refusing to leave the scene and move away as the police wanted him to, Mr Hinds deliberately made the situation worse.
“Mr Hinds could see and knew it, nevertheless by his behaviour, moving in and refusing to leave and continually shouting out, he was determined to note down the telephone number despite the fact that it was clearly causing Thomas Edwards to resist.”
She added: “He came up close enough to PC Cousins for his head to collide with the officer’s cap.
“The spontaneous outcry recorded on footage clearly supports this.
“The was no reason or opportunity to invent a false allegation of assault. I prefer PC Cousins’ evidence.
“I am sure Mr Hinds got too close and was being aggressive with PC Cousins.”
The judge said she was “quite sure” Hinds pushed the officer, adding: “His head collided with PC Cousins’ cap while he was acting aggressively towards the officer and I find him guilty for these reasons.”
Hinds, who is also a youth worker and chairs a stop-and-search monitoring group in Haringey, has previously received a £22,000 payout from the British Transport Police after a similar case against him was dropped.
He has also advised BTP’s stop and search consulting group.
Referring to his work in the community, the judge said: “Whilst not a man of good character, now aged 59 and well regarded within the community in Haringey, I have taken into account in his favour all these activities and how they informed his decision to intervene in the events on April 16.”
She added: “I don’t doubt the real and valuable contribution he has made to improving relationships and working with local police.”