The man, said by police to be 65 years old, was arrested on suspicion of assault in Essex yesterday. He was taken to an east London station and released on bail for a date in early November. Separately a 46-year-old man was interviewed under caution.
Police are still appealing for information to identify four other men in connection with the same incident, in which a security guard was knocked unconscious after a number of protesters - calling for greater regulation around private car hire, particularly Uber - stormed City Hall during Mayor's Question Time with Boris Johnson last week.
The United Cabbies Group today issued a statement saying the man who had been arrested was "not a taxi driver" and urged "ideological protest groups" to stay away from future demonstrations.
A spokesman for the Metropolitan Police told City A.M. was unable to give any further detail about the man, who is yet to be charged.
Thursday's Demo at Bank Junction is a Taxi trade Demo members of ideological protest groups we ask you respectfully to stay away— UCG CAMPAIGNS A/C (@UCGcampaigns) September 21, 2015
A spokesman for the UCG said: "Violence is totally unacceptable. Taxi drivers are subject to in-depth criminal background checks before even being handed a badge. Contrary to some media reports, the man arrested last Wednesday is not a licensed taxi driver. It appears he had simply tagged along.
"We respectfully ask that members of ideological protest groups keep away from our future demonstrations."
The UCG said it was "working closely with the Metropolitan Police to safeguard public safety at its future protests".
Our Demo on Sept 24 will be under supervision of COL Police.— UCG CAMPAIGNS A/C (@UCGcampaigns) September 20, 2015
Please follow their instructions.
They are there to help .#Good Relationship