Company Director George Eales, 25, boss of ACTA PACIFIC FX joined in the late-night assault, triggered by his employee Alex Kit Perrotton, 22, landing the first blow.
Both were convicted at City of London Magistrates Court of assaulting Tim Miles at Shake Shack, Leicester Square on September 8, last year.
The third member of their international payments team, aged 17 years-old, was also caught on CCTV swinging punches at the victim and was dealt with separately as a juvenile.
“This has made me second-guess people when I am out in London as I had never been attacked before,” said Mr Miles in his victim impact statement.
“They were dressed in suits and I thought they would act respectfully, but they acted like animals.”
Eales, of Albemarle Road, Beckenham was fined £865, with £385 costs and ordered to pay a £346 victim surcharge.
Perrotton, of Wickham Way, Beckenham was fined £692, with £385 costs and ordered to pay a £277 victim surcharge.
“I have never been in a fight before and I was just being hit,” Mr Miles told the trial.
Prosecutor Sharon Michaels told the court: “This was at night and must have been a frightening scene for the people there seeing what was going on.”
The prosecutor told Eales: “You came back in and attacked him. You ran back in and we can see you thump Mr Miles at least two times.
“You were not under threat and you just joined in. You came barging back in and start hitting Mr Miles. You were not trying to break it up, if you were you’d be pulling your 17 year-old colleague away.”
Eales claimed he was trying to break-up trouble started by Mr Miles and a friend of the victim, who were in front of the trio in the queue.
“It was the first team night out, I own a payments company,” said Eales, estimating he had four halves of beer that evening.
“There was just jovial banter between the two groups, but then the atmosphere started to turn.
“The complainant and his friend in a striped t-shirt were aiming quite a lot of aggression. The complainant became very much the aggressor with his friend and was rude and threatening.”
Eales claimed Mr Miles was “picking on” the 17 year-old, threatening: “I’ll see you outside.”
The five foot, six inches tall Eales claimed he was intimidated by the larger, older man. “Any contact I made was to break it up.”
The trio fled the burger bar and were chased and caught by police. “That was an error of judgement,” said Eales. “I did not know how to react.
“We all felt we were under the threat of violence.”
Perrotton was caught on CCTV landing the first blow, a slap to Mr Miles’s face. “I felt it was appropriate to defuse the situation with an open-handed slap,” he told the trial. “I was not my objective to hurt him.”
He also claimed the other group were the aggressors and were encouraging other customers to jump the queue in front of the defendant’s, while blocking their path.
“We were started on by two fellahs older than use and bigger than us and the striped t-shirt male was shouting: ‘F*** him up, weight him in.’
“The complainant was leaning forward towards out group saying nasty, horrible threatening things.”
Prosecutor Ms Michaels asked Perrotton: “You just slapped him around the face didn’t you? You decided to slap him, you were not under threat.
“The man is just paying for his burger and he was not showing a threat or being aggressive.”
Mr Miles was left with red marks to his injured face. “It is quite obvious where the injuries to his face come from and the lack of injuries to the defendants shows where the truth lies,” the prosecutor told the court.
Perrotton disagreed, telling the trial: “I felt quite threatened myself. It was an open-handed slap to defuse the situation.
“You can see him (Mr Miles) leaning over and he starts the argument again. It does not make sense for me to go around hitting people.”
Ms Michaels told the magistrates: “It was a single slap, but is seemed to start off everything and this ended up as a group incident and there was bleeding on the complainant’s face.”
Convicting both first-time offenders magistrate Colin Gregory announced: “Regarding Eales he can be seen approaching Mr Miles and delivering two blows to him.
“He was punching him to the side while the victim was already being attacked.
“We reject the claim of self-defence in relation to Perrotton and the suggestion the slap to the face was to defuse the situation is not credible.”
The first-time offender was told by the magistrate: “Mr Miles was not an immediate threat and there was a security guard between the two of you.
“You are both of good character and there was an element of provocation here and we cannot be sure what injuries Mr Miles sustained from your conduct.”