I should like to clarify the issue in this dispute. The question is not whether the blog is a 'source'; it is clearly not a source for anything other than what is said on the blog. The issue is whether or not to mention it in the article; the subsidiary issue is, should that question be answered in the affirmative, it should be linked to.
My position is that the answer to both questions is Yes. The following reasons justify mentioning the blog:
1) The blog has been mentioned twice in the (UK) national press. The first was in Damian Whitworth, "A strange case of espionage and warfare inside the commuter belt", The Times, April 18, 2005, p. 28. The second was Rod Liddle, "Battle of the Guildford gals", The Sunday Times, May 1, 2005, p. 15. I have undertaken an extensive search and have yet to find any other site set up to target an individual candidate being mentioned in the press. This is therefore a unique situation.
2) The blog has also been mentioned by Sandra Howard (wife of the then Leader of the Opposition) in her election campaign blog. http://www.conservatives.com/tile.do?def=sandra.howard.page&obj_id=12274...
3) The fact that Anne Milton is quoted by Sandra Howard asserting that Tim Ireland was "stalking" her through the weblog is particularly significant. It is a notably extreme accusation.
4) It appears to be the only case where a blog about an MP has continued to be updated. There have been others, but they have all gone under. This one hasn't.
5) The author of the blog, Tim Ireland, is notable enough to have an article about him. His notability is for his work on political blogs.
6) I do not propose to mention this in the article, but in my submission the edit wars engaged in by supporters of Anne Milton (including by IP addresses traced to the Parliamentary estate) who attempt to remove all mention of it from the article, denote that it is considered notable by them. See the article history.
I do not see how WP:BLP is engaged merely by mentioning that a critical blog exists. It is potentially engaged by reporting Anne Milton's reaction, but that has an unimpeachable source in The Times piece.
Now Guy imputes to me motives other than improving the encyclopaedia to explain why I think it should be mentioned. This is really neither here nor there to the merits of the case but I would invite anyone wishing to examine the issue to look at my contributions on Talk:Anne Milton starting in June.
Should the first question be decided in the affirmative, that the blog is notable enough to be mentioned, then should it be linked? I submit the answer is clearly "Yes". Once the article mentions the blog, inquiring readers may wish to look at it for themselves. It simply makes no sense to say that the blog is notable but yet not linkable. Even the Wikipedia article on Goatse.cx links to a mirror to it. I would make a proviso that the link to the blog should make clear that the site is not in any sense neutral. It might also be reasonable, though I don't think warranted, to have the site address in text rather than as a hyperlink.
Perhaps I should say that as I understand Guy's position, he considers that a link to the blog is acceptable from [[Tim Ireland]] but not from [[Anne Milton]]. I cannot understand the internal logic of such a position.