Council officials were forced to suspend a contractor who threatened a group warning motorists about the presence of the CCTV cars.
A group called NoToMob, so outraged at councils making millions through the traffic enforcement vehicles, were in Sutton on July 20 and followed them around the borough to let people know they were being watched.
Although the day started peacefully, with a chat with police explaining their plans, it ended on a sour note when they were confronted by a member of staff at the NSL offices.
A contractor from NSL, which runs the CCTV cars, was suspended after the protesters made a formal complaint about him.
A group member, who goes by the name Bald Eagle, said: "He concluded the rant by suggesting we meet one night after work so he could 'sort me out'.
"When asked if it was a threat, he said he didn't make threats he made promises."
A Sutton Council spokesperson said: "A thorough investigation of the facts has been carried out following a reported incident in July.
"This investigation has now concluded with appropriate disciplinary measures taking place.
"Following the incident, NSL issued advice to all staff about NoToMob."
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