Good grief, bring on Icke and his lizardmen while we're at it....
1) even if Tony Blair really intended to do such a thing, you're assuming that nobody else in the US political hierarchy actually has any say in who they go to war with or can influence that final decision. Don't you think one or two others in the US might have spotted it if Blair were pulling Dubya's strings? Like the senate, congress, or his own government appointees? It's vice versa, and has been for the past 60 years. In the normal run of things having a war is a vote loser, especially a distant one where there are no obvious gains to be had from it.
2) In the unlikely event that the aim of a labour government were indeed to destabilise the major world economy (and what a wonderful day it'll be over here when the US goes kaput, eh?) I can think of several dozen better, more sure, more effective ways to do it than to encourage him to invade Iraq.
3) It's entirely likely, in my view, that the decision (both in the US and the UK) was sincerely based on a suspicion of MWD, as more than one cynic has pointed out 'we know he had them, we sold them to him'. The suspicion being based on imperfect intelligence (you need people on the ground, and I suspect the SIS, CIA etc had few well placed 'assets' passing hard information back) and Saddam's brinkmanship - and SH played that game like a complete ham... apparently because he was more afraid of Iran realising he didn't have any MWD (thus inviting them to resume the Iran/Iraq war) than he was of a US invasion that he figured it'd be easier to avoid.
4) A bigger question, in my view, is why - having shown the resolve in Iraq - wasn't N Korea in the frame prior to that? I can only imagine that the US record in Korea was a big enough worry to ensure North Korea wasn't an earlier target, especially considering how well Gulf War 1 went.
Politics is never straightforward, and cynicism is a useful tool, but just making ideas up out of thin air is pointless and as likely to hit the bullseye as any other randomly projected dart.
Dave