Leading article: Authority cannot be rebuilt in a day

So this is the fightback. At noon yesterday a visibly chastened Gordon Brown offered himself up to the media he had declined to meet on Saturday – and tried to sell them the same old story about his election decision not being influenced by the polls. He then went to the Commons to impart the good news that the British troop presence in Iraq could be halved next spring, only to find himself forced to revisit the first principles of the invasion, including his own complicity as a senior member of the Cabinet.

The Downing Street press conference was lacklustre. Mr Brown knew it; the assembled reporters knew it. The Prime Minister tried to look stoical, as though he knew this was an ordeal he had to suffer, having largely precipitated it himself. His answers were from the rote-learning school of politics. He gave not an inch on the reason why he had decided against an election. The incredulous reception far exceeded standard journalistic scepticism.

If Mr Brown had hoped that his Commons statement on Iraq could save the day, he was sorely – and almost embarrassingly – mistaken. The mood of MPs was, if anything, more sceptical even than that of the journalists. At times it bordered on contempt. By making Iraq the subject of his first policy statement of the new Parliamentary term, the Prime Minister merely reminded MPs of perhaps his greatest self-inflicted wound: the day-trip to Baghdad and Basra in the middle of the Conservative Party conference, where he had made an announcement about troop cuts that turned out to be far less than they seemed.

Clearly scenting his advantage, the Conservative leader in his response was unforgiving. He began by drawing attention to Mr Brown's earlier undertaking to make such announcements in the first instance to Parliament. He went on to decry the use of British troops for party political purposes. The Prime Minister was already on the defensive well before he was buffeted by Sir Malcolm Rifkind and Charles Kennedy (among others) about his part in Britain's march to war. Tellingly, perhaps, the longer his torment went on, the more his replies lapsed into the familiar cadences of Blair-speak – a dialect to which we had joyfully bidden good riddance after the plain-speaking Scot entered Number 10.

It is hard now to imagine how Mr Brown's Commons statement might have been received had he not made that ill-timed and ill-conceived announcement in Iraq; had the Conservative Party not trumped Labour with its coup on Inheritance tax; had Mr Cameron not delivered his tour de force without autocue; had the Tories not been scared into unity by an election threat. But it is worth considering, all the same. If Mr Brown had stood up in Parliament yesterday as he appeared through the summer, as the solid, responsible son of the manse, his statement might have been hailed for what it probably was: a radical shift from Mr Blair's policy in Iraq and the announcement of phase one of Britain's withdrawal from Iraq.

As it was, Mr Brown failed to convince. He did not even offer the modicum of moral decency we had hoped for on the treatment of Iraqi interpreters and others who have thrown in their lot with British troops. The offer of financial help to go into business or resettle outside Iraq – but preferably not, the message came over loud and clear, in Britain – was cautious meanness at its worst. We trust that this will not be the last word.

Yesterday was not quite Mr Brown's very own Black Monday. Black Saturday and Sunday had made it hard for his plight to worsen. It was rather an illustration in two chapters of the damage already done – and the scale of the task that lies ahead if he is to repair it.