...no-one believes that comments threads on British political blogs are representative of the wider view of the public...
Fair enough comment Tom. Here's my take.
The first widespread internet - i.e. Usenet/Netnews did tend to have a libertarian bent because that is very often an attitude that goes with computer knowledge and a certain sort of nerdiness.
Of course all that changed the day AOL allowed it's (mostly dumb) users on to the net. The moment that happened the net swung right.
Since then, at least in the US, a left-wing blogosphere has grown up in opposition to Bush.
I think part the reason the left is less prominent on the net in the UK is that supposedly a "left" party has been in power, and secondly, left politics in the UK has always tended to be more sectarian than "liberal thought" in the US.
If we get a Tory government, I think a real "net-roots" movement will develop here.
Finally, and I am sure I am prejudiced here, I think political progressives *tend to be* (i.e. not universally) better educated and more inclined to developing systematic thought that those on the right.
This leads to left wing bloggers writing essays rather than blog posts.
On the net, you need to know how to sock it to 'em in a one paragraph sentence...