No, Lee, you are wrong.
Not about the law -- I am happy to take your word on that.
However, you are wrong that avoiding surveillance is suspicious. And you are wrong that police guidance should not make it completely clear, to every constable, that it is unacceptable to society to have police stop anyone because they are refusing to be photographed. Just like it is unacceptable to society to have people stopped and spoken to because they are taking photographs. Neither activity is suspicious. Neither activity should interrupt someone's enjoyment of the public street.
Your example of the person walking near a burglary is irrelevant. Then a crime has been committed and the police need information from witnesses as well as a heightened level of suspicion of anyone who might have committed the crime. All reasonable.
There is no requirement that we assist the police. If they want to take photos in public that is up to them. But they have no more rights than anyone else doing that. If I don't want to be photographed that is equally my right. Applying coercion, by having a constable lurking ready to stop me if I avoid being photographed, is not acceptable and needs to be clearly banned if this technology is to be used for real.
Bottom line: hiding from surveillance is not grounds for suspicion and will not be accepted as such. That needs to be made very clear to every officer involved.