http://www.guardian.co.uk/uk/video/2...ri-lanka-tamil

"Tamil protesters clash with police

Thousands of protesters take to the streets of London to demonstrate
against the treatment of Tamils in Sri Lanka"

I repeat, it is the police who close the streets.

That video shows the police trying to get people off the road; but
they keep jumping back in.
Why don't they protest at the Sri Lankan embassy?