Anthony Cox, the author of the page, now tells his story in an article in the Guardian (via Up2Speed). It's a really interesting case study for viral marketing by accident:
"After favourable comments from friends, I posted it in the newsgroup uk.rec.humour . Within the next 24 hours, the website had had 150,000 hits and had propagated to 118 newsgroups. By the end of February, it had received more than one million page impressions. Perhaps the ultimate accolade was having the original email come back to me with a note saying: "Have you seen this?" Visits declined throughout the subsequent war, and I suspected its 15MB of fame had passed.
Yet, suddenly, in the first four days of July I received nearly 4m page impressions, more than the previous five months combined. The reason? Typing "weapons of mass destruction" in Google and hitting the "I'm feeling lucky" button did not bring up Number 10's "dodgy dossier", but my spoof site. Suddenly, it was a lot funnier and accessible: even Google couldn't find the WMD."