Socialist Workers: never at work?

I had some difficulty walking across Parliament Square today because there were a lot of Socialist Worker protesters holding up signs saying that Bush was the world's No. 1 terrorist. Well, I personally don't think that's true at all, and I was someone who wrote their dissertation on why the conflict in Iraq was illegal and unjust.

But what struck me is how these people are also environmentalists (who,according to their high quality paper are in favour of solar panels and eco friendly council houses) and yet they have spent an entire day blocking up a major traffic route in London causing congestion and therefore more carbon emissions.

How did they also manage to get so many of them there, instead of being at work? They hadn't just come from some office as they were all in track suits and other delightful items of clothing not conducive to a professional career. They seem to manage to get large numbers of people to all their events. Do they, despite being called socialist workers, actually work?