The drunk man was accused of touching a woman as she walked past him at the fast-food chain in Market Square in the early hours of July 20.
He was berated and punched inside McDonald’s before being followed into the street by a group, thrown to the ground and repeatedly punched, picked and kneed in the head.
A Met Police spokesperson said CCTV enquiries proved that the sexual assault allegation was “false”.
Alfie Buck, 29, of Riverpark Gardens, Bromley, described as the “ringleader” in the assault, was given a suspended sentence at Bromley Magistrates’ Court on Thursday, October 9.
Prosecutor Colette Hanna said Buck was inside the McDonald’s when he became aware of the man being berated over an alleged sexual assault.
“The defendant joined in and punched the victim. Security then ejected the group at which point the defendant followed the victim down West Street, grabbed him by the hood and threw him to the ground,” Ms Hanna said.
Buck punched and kicked the victim to the head and encouraged an unknown man and an unknown woman to join in the assault, the court heard.
He then took the victim’s phone and threw it away before leaving the scene.
Emergency services were called to assist the victim – who had bruising, scratching and blood coming out of a cut to his ear.
Ms Hanna said: “Irrespective of what the allegation is, there is little justification for that level of attack on a man who is clearly drunk.”
Buck pleaded guilty to assault by beating and theft of a mobile phone.
Buck told the court: “I was under the influence of drugs and alcohol myself. I deeply regret my actions.
“I know I shouldn’t think I’m a superhero and take the law into my own hands. I’ll calmly call the police next time.
“All I can say is I’ve learnt my lesson and I’m sorry.”
District Judge Sarah Turnock said: “This offence is undoubtedly very serious. The assault you perpetrated was persistent and sustained.
“You returned to him lying on the floor, posing no threat, on multiple occasions.
“You used your knee to knee him in the head, you kicked him to the head on at least two occasions.
“His head landed with considerable force on the step of a shop door he was resting. You then grabbed the back of his hair and encouraged others to come and join in the assault including an unknown male and an unknown female.”
Judge Turnock said what the victim was accused of doing did not justify his action.
“In fact, I note that you weren’t even one of the people initially involved in the altercation which suggests that really you just wanted to be involved in the physical side of things,” Judge Turnock said.
The judge said that the assault justified a custodial sentence, but she decided to suspend the sentence due to the impact a prison sentence would have on his pregnant partner and their child.
She also noted that Buck had shown genuine remorse for his actions.
Buck was sentenced to 16 weeks in custody suspended for one year.
As part of the sentence Buck was ordered to abstain from alcohol for 90 days.
He was also ordered to pay £250 compensation to the victim.
