Here's what happened:

"Started off in Hyde Park, with a temperature in the early 20s celsius, bright sun and a mild breeze. It was already extremely noisy when I arrived, and the cops were standing about with that "Overtime, overtime" expression on their faces. Always nice to have their sympathy. Ranks of vans were situated about the place, especially up near the Marble Arch. The march stretched back to some distant end of Hyde Park that I didn't care to amble down to. The drummers were there - ba-dah dah dah dah dah, ba-dah dah dah dah dah etc - as were an inordinate number of whistleblowers. The wrong kind of whistleblowers.

Eventually, the police let us bugger off on our way and the march proceeded down to Park Lane before taking a detour up some bloody road that I had never been down before. Turned out we were going to hi-jack the American embassy and issue demands: "We want some helicopters and pizza, you capitalista fucks!""

More:  http://leninology.blogspot.com/2005_03_01_leninology_archive.html#111127878438828076