Just as the sporadic pockets of celebration at Saddam's defeat have been swiftly replaced with anger in Baghdad, so the mood in the corridors of Westminster has also noticeably darkened, writes Alexander Alistair in London Tony Blair felt sure enough of his position last week to confide to the trenchantly pro-war Sun -- his favourite newspaper -- that he was all-but-ready to resign if he lost the crucial vote in the House of Commons two days before the invasion of Iraq began. "In the end, it is a decision you put the whole premiership on the line for," he mused, apparently casually. But then, having been continually criticised since coming to office for lacking any substance, Tony Blair has now been reborn -- in the eyes of Blairites at least -- as a conviction politician. There was a brief window of calibrated triumphalism from Downing Street after tanks trundled into Baghdad. But this interview probably marked the end of it. "In the end if you lose your premiership, well you lose it," he said coolly. "But at least you lose it on the basis of something you believe in." Belief is one thing; evidence is quite another, however. And on the awkward issue of weapons of mass destruction, even his most loyal supporters are privately wondering whether their leader let his beliefs run ahead of the facts. The depth of feeling against the war has certainly not dissipated, as the government had hoped; but it has diffused. Whereas the inexorable drive to war presented a single focal point around which all dissent could easily unite; now, that opposition appears to have lost its clarity. The anti-war movement has been superseded by more intangible worries of empire, occupation, global disorder and Britain's tattered relationship with Europe. It's no surprise, then, that many opponents of the war see Saddam's elusive weapons of mass destruction as the defining issue through which pressure on Blair can be maintained. The government was hoping the soft afterglow of military victory might linger for a while yet before this delicate issue had to be addressed. After all, as ministers never tire of saying, Iraq's a big country with a lot of dark corners to investigate. But the public's patience is rapidly wearing thin. One newspaper, the anti-war Independent on Sunday, ran the headline "So where are they, Mr Blair?". The very fact that, even in its dying gasps, the Iraqi regime failed to release the smallest trace of nerve gas was more than enough to raise suspicions that perhaps Tony Blair's imagination might have got the better of him. Since the collapse of the regime, the US military has loudly announced "suspicious" finds on at least four separate occasions, only for them later to be quietly forgotten. One such find of alleged nerve agents turned out to be pesticides after further testing. The soldiers who became nauseous when inspecting the pesticides were, in fact, suffering from dehydration. Another suspicious site was actually a farm building, as the US army rather sheepishly admitted later. And of course, for Blair, it hardly helps that, having gone to war for Iraq's apparent failure to cooperate with weapons inspectors, the White House is now preventing Hans Blix from returning to the country -- a far more brazen violation of Resolution 1441 than Saddam could ever muster. British ministers earnestly assure their critics that they support United Nations inspectors returning to Iraq. But they must also have been aware that the US administration decided to conduct its own inspections back in December. Needless to say there wasn't a word of protest from London then, when they might have actually done something about it. But you can't fault the United States for effort. The New York Times reported on Monday that a mysterious inspections team called MET Alpha was in contact with an Iraqi scientist who claimed that Saddam had "destroyed chemical weapons and biological warfare equipment only days before the war began" and that the regime had transferred "unconventional weapons and technology" to Syria. Even more conveniently, the scientist has also claimed that Saddam had been cooperating with Al-Qa'eda. How the scientist discovered this remained unclear, however. MET Alpha, it transpires, are part of the Defence Intelligence Agency, which, incidentally, is under Donald Rumsfeld's control. The reporter was not allowed to learn the scientist's name or interview him lest she "jeopardised the scientist's safety". Happily, however, the journalist was "permitted to see him at a distance", as he was pointing out to the inspections team where illicit weapons were apparently kept before they were destroyed. "It may be the major discovery," says one major general, somewhat hopefully. But this is precisely the kind of embarrassingly unconvincing discovery that Blair could well do without. Now British MPs are mounting a concerted campaign for an inquiry into whether the government was misled by intelligence agencies about Iraqi banned weapons. Although British intelligence no doubt has questions to answer on the issue, few could miss that the real target of such an enquiry would be Blair himself; Labour MPs don't want to appear openly mutinous just yet. Foreign Minister Mike O'Brien has brushed off the demands: "It is the case that Saddam has been hiding this stuff and therefore I think all these demands for investigations are more than a little premature," he said. But the calls could get harder to ignore, as weapons continue to remain somewhat conspicuous by their absence. No one should have needed the benefit of hindsight to realise that the apparently "irrefutable evidence" of Saddam's illegal weapons was, on closer inspection, anything but. Every piece of evidence presented by the British and American governments was unsubstantiated, discredited or, in some cases, completely fabricated. But somehow, Blair's prodigious powers of persuasion were just enough to see him through most domestic scepticism. Many assumed he was simply too passionate about weapons of mass destruction for it not to be true. Others thought it inconceivable that Blair would launch a war on a false premise that would almost certainly be found out -- he just wouldn't be that stupid. Whatever the truth, there is little doubt that Blair certainly persuaded himself of the existence of weapons of mass destruction in Iraq. In the build up to war Blair routinely fell back on dark hints of what he knew but couldn't possibly make public, to protect intelligence sources -- naturally. But now that the regime has gone there is no reason why the sources require further protection. So far, however, such privileged information has been unforthcoming. Having proclaimed so frequently that time was running out for Saddam to declare his illegal weapons, it seems that precisely the same clock is now ticking for Tony Blair.