Bit hazy on this, many years ago for my DoE Awards we had lectures from the police. One of the points was that after I think it was 8pm, they have the right to ask your name, where you live, and where you are going, and you have to tell them. Before this time in the evening they can ask, but you don't have to answer. (But it is politic to do so if it won't cause you a problem).
Clearly evasive young guys hanging around on an estate, acting suspicously, are going to get a tug, and quite right too. Typically they are either dealing, buying, or going equiped for a crime such as mugging or burglary.
Recovery of items after seizure by the police is a big problem, always was, often got mislaid/lost/damaged etc.
One historical short rifle legally owned by a work colleague, and ordered to be returned by the Court, was literally seized by the owner off the (very) senior police officer who was using it during a shoot a year later! (West Yorkshire Constabularly) No action taken against the officer.
The various gun Associations are now instructing members to refuse to pass them to police when asked for them, and to legally elect instead to take them to a licenced gun storage business. Happened recently to someone I was working with, who explained it to me, and got his rifle back.
Police are now getting very clever at hiding their number and not answering if you ask for their number. It's a common smokescreen demand by ne'er-do-wells, and an equally common police tactic (" he was making so much noise I was distracted and don't recall hearing him ask sir")
