Harassed in Greenwich (?)

My friend and I were harassed (I think?) yesterday by a guy seemingly from an environmental watch or something... He had a vest but we didn’t pay attention to his credentials. He seemed to be wearing a camera too.

My friend and I were chatting outside of Greenwich DLR station (by the Joe and the Juice) while she finished her cigarette before we started walking. The guy came up from behind me, bumped into us and started following us and said that we committed something (mumbled), we need to provide him contact details otherwise he will call the police and we get fined and arrested. He was speaking into a walkie talkie of our whereabouts, so the police can come arrest us (?). My friend had panicked a bit and we walked faster, as she thought he was trying to fine her for chucking a cigarette butt. However she hadn’t thrown anything on the ground because she later realised she had stuffed it into her empty Coca-Cola can, as she usually does. He followed us across streets and into the market until I Iost it, faced him telling him to stop following us. He eventually left while still threatening us with the police. Maybe it was us who should have called the police actually.

I am baffled: was this a random dude wearing a vest trying to harass women? Was this legitimately somebody from the council enforcing littering charges? (Again, my friend did not throw anything on the ground, she put the cigarette butt in her Coke can which she kept hold of until after all this and it’s how we realised we were maybe just followed by a weirdo.)

Is this something I can report somewhere or is it just part of life idk.

Sorry for the long rant. I am just baffled.