Who Are These People?

Can anyone tell me what a 'Metropolitan Community Police' Person is? Holborn and the West End seems to riven with them? I can't walk down the street without having to sidestep little clutches of them wandering about in their Police alike uniforms with dayglo orange jackets. Presumably the jackets are so they can't sneak about looking unobtrusive like a proper Copper should.

Can someone please explain?

The bag man seems to be watching them to. Maybe he's bored, maybe he's MI6, who knows?