Not much protest in 2004.
Some years anarchists have hijacked the annual labor protests at Trafalgar Square, leading to ugly confrontations with police. In 2004 it was not such a disruptive event.
There were policemen and demonstrators present, but things were calm. Flags and banners were waved. Protesters shouted and chanted. Policemen leaned on a wall and watched.
Looking at this view it hardly seems like there was a May Day labor protest going on. (Around the corner there was more visible protesting, but nothing violent.)