Around 150 people crowded into the Arbour youth centre in Tower Hamlets, east London, on Friday night for a public meeting. They had came to show solidarity with Zac Hussein, a youth worker at the centre, who says he was attacked by the police.
A video of the incident, which is being circulated on social media, appears to show two police officers holding Zac down.
Another officer appears to say “Why are you spitting at me” before advancing on Zac, putting him in a headlock and pulling him down.
Shortly afterwards the video ends.
Zac says he did not spit at the cop.
The officer has not been suspended. The Independent Police Complaints Commission (IPCC) is investigating the incident, but Zac is also being investigated by the police.
Sue Williams, the borough police commander, said in a statement, "On Saturday, 8 October Neighbourhood Officers from Tower Hamlets were out on routine patrol in Shandy Street, E1.
"They spoke to some young men due to concerns about anti-social behaviour in this area.
“At 8.10pm the officers called for additional assistance. One man was arrested on suspicion of assault on police and a section 5 Public Order Act Offence.
"He has since been bailed."
Zac spoke at Friday's meeting, pointing out that he could lose his job if he is charged. "I'm a normal guy, I work with kids," he said. "I was scared they were going to pepper spray me or taser me.
"If I didn't have the video footage it would be my word against theirs."
Local politicians, including Labour mayor John Biggs, attended the meeting. Tower Hamlets First councillor Rabina Khan spoke about how she asked the borough commander to make a statement about the incident.
"She did nothing,” said Khan. "She emailed back an inflammatory response which I'm not going to read out here."
Zac went on to point out the huge inequalities in the area, "We've got Canary Wharf on our doorstep but there are people here who can't afford to turn their lights on."
The IPCC is not fit to investigate the police. It emerged last week that irregularities with investigative procedures have led to the IPCC itself becoming the target of a criminal investigation.
The campaign for Zac has won the support of people in the area and local politicians. It can put pressure on the police to take disciplinary action against the officer and drop the charges against Zac.