A UK photographer who goes by the moniker Hamstify was documenting his town Scunthorpe late last year when he was confronted by security personel outside a Golden Wonder plant and ordered to stop photographing. He was shooting from a public location, so he decided to stand up for his rights and film the argument that transpired. On VisitScunthorpe.com, he writes,
What also aggrieves me is that someone in a uniform representing a company in an apparent position of authority can try and intimidate members of the public by making up laws that don’t exist. This seemed to be an attempt to subjugate a member of the public into accepting what was being told was to be true. Further more hurling offensive insults and puerile slander, like seen at the end of the video, surely isn’t something that someone in that position should resort to.
In general, for UK residents, photography from public places is perfectly legal. There are some exceptions (e.g. buildings critical to national security), but the general rule of thumb is that if you’re shooting from public property police and security guards don’t have the power to stop you.