OK
So why the physical force?
Why the need to restrain someone in the course of their job?
Why the need to "borrow" (read :steal ) this guy's phone?
Why the need for search, when he obviously was already offering to comply with requests?
Why not simply question him, without the need for force? Why not simply speak to him like a human being, instead of treating him like some piece of drunken scum? Why not ask politely, what he was up to, why he was doing it? Why not ask for confirmation of his work to verify he was working on an assignment?
I thought the police were supposed to be all community support and gently, gently? Nope! Easier to come down hard knock a few heads, "Dat'll learn 'im proper sarge!".
Yes, there are good ones and I seem to have been lucky. The police have questioned me once while I was shooting shots off a bridge late one night. They came over and asked in a polite tone, what I was doing and why it was here? I told them exactly what I was up to, showed them the camera and they were happy. They even apologised for bothering me. That's the first step, to building trust. Not freaking hog-tie someone up and steal their stuff!!!