is there such a specific law? I do not think so, I stand to be corrected if anyone can point out the Act and section.
One would think it would depend on the circumstances whether a breach of the peace would be likely to occur (for instance someone in a public park taking pictures of children and has been asked to stop and fails to do so causing parents to be upset and angry) then an arrest by a Police Constable in uniform COULD be made but the circumstances to cover a breach of the peace or any public order offence would have to be right.
Even signs prohibiting the taking of photographs are strictly NOT lawful, unless there is a local by-law governing the site where the signs refer to.
Whether it SHOULD be allowed is different than NOT BEING allowed.
There endeth todays lesson
Yiou are wrong Lynda any illegal photos are NOT allowed to be used ie copyright ones.