bovlomov wrote: ... There must be dozens of studios and meeting rooms where such interviews could be conducted. I'm not sure why they need to do it al fresco. News broadcasters seem to think reports are more immediate (or up-to-the-minute) if they are filmed outside. Most often there is absolutely no benefit; the reporter has no more information than if s/he was sitting in a studio.
"I'm standing in the street, and in that building behind me something is happening. In a while we'll see some cars driving away. More as it happens!"
This doesn't just apply to politics, of course. If there's a big soccer match where they don't have the reporting rights, the BBC will have a reporter outside the ground telling you what's happened inside. There's a big temptation for passers by to get behind the person talking to the camera and wave to their mum, put rabbits' ears on the tv presenter etc.
College Green, Westminster, is somewhere it suits both the media and politicians to conduct interviews, partly for convenience, perhaps more because it gives that air of immediacy. The media and politicians have a symbiotic relationship: eg note how often the interviewee is filmed gormlessly walking across the shot before the actual interview. With all the people doing media studies, plenty of people have picked up on things like getting a poster into the shot where it's often much more effective than background shouting which is faded out.
With a lot of staged media opportunities, the parties have their own minders to keep anybody away who might spoil the cosy image and they use other tactics like keeping the itinerary secret to the last possible moment so only supporters/ sycophants are in the know.
That's not to excuse violent or abusive behaviour but some of it is predictable.