we've had agent provocateurs since back in the ant-Vietnam war & CND marches.
One who belonged to our small group turned out to be a Special Branch officer. We always knew he was a fake..beard and hair too long, flares too flared, too many beads and anti-establishment badges.
In the end we had loads of fun with him and worked out how to surround him in a crush and hem him in-always telling him to calm down and not respond to taunts. Poor thing, it must have been very frustrating.
He was actually good fun to go and have a drink with at the pub. I saw him years later in the street and we chatted briefly-he was then pretty high up at Scotland Yard. He said he actually believed in our cause..but he had his job to do.(and he said his wife loved his hippy look)