This story might be more about UK police abuse of power than anything else.
The first officer that talked to Mr. Cameron said what he was doing was perfectly legal. Then a second officer came along and arrrested him.
Video of the incident here.
https://youtu.be/T6lsyAcUnJQ?si=St-uCq5pRCrJJsx8
I would think a review of every arrest by the 5 officers should be undertaken. I would easily believe this is not the first time they have been bullies.