I don't want to go into too much detail, so hypothetically...
If a 'private' security firm had been hired by the council to enforce anti littering/street urination with the power to issue a fine to members of the public. How would that work? If they stopped you in the street and said they had seen you throw litter etc, how can they fine you if you haven't given them your name and address? And what powers do they have to detain you until you give them that information? How would that work for an under 18 year old (especially if under 18 year old doesn't smoke so didn't throw a fag butt on the floor!)
Could you just walk away and refuse to engage?