Didnt see it in the end (didnt have time to even walk the 30 meters from my office round the corner to the "front entrance"  to scotland yard and it didnt pass my window), but according to the evening paper there were "hundreds"  i think mainly NUJ so Journalists (figures really considering they are most likely to fall under the law)... bbc website has it too:

http://news.bbc.co.uk/1/hi/uk/7888301.stm

"In every colour, there's the light.
In every stone sleeps a crystal.
Remember the Shaman, when he used to say:
Man is the dream of the Dolphin"

Rich Meadows Photography