This brightened up Tory spirits that were decidedly low at the start of the session. The recent polls had put them in the doldrums and they looked sad, chastened and thoroughly dejected. For Mr Duncan Smith, facing them later in the day at a meeting of the 1922 Committee, this question time was merely a practise run. It started badly but he had only used two bullets out of his ration of six They were about Iraq – and misfired. But, just as we were about to write him off, his capacity for surprise – by which he won the leadership against the odds last year – gave him the best one-liner of his career. "Isn't it the case that when the Prime Minister makes promises on schools, transport, pensions, or for that matter on crime, asylum, drugs or health, he's not juggling balls – he's talking them?" It was a Christmas cracker of a question – even though Michael Heseltine, Mr Duncan Smith's b? noire, inspired it.

Lord Heseltine had used a similar line, years ago, against Gordon Brown and his adviser Ed Balls. But IDS surprised everyone: Tory MPs, Labour MPs, the Prime Minister and even himself at his success. It was cheap, it was below the belt, it verged on the unparliamentary (had he cleared it with the Speaker, I wondered, as he nodded to Michael Martin afterwards) but it was a winner.Mr Blair looked taken aback. This was a day he had to score, not least because his eldest son, Euan – he of the Bristol flat – was home from university and watching in the gallery, no doubt expecting Daddy to trash IDS Unfortunately, Daddy got punched in full view of Euan How embarrassing. And how satisfying for IDS as he marched off to quell, albeit temporarily, any trouble in the 1922 Committee..

W hen, a few years ago, Charles Kennedy was languishing as the Liberal Democrats' agriculture spokesman, he made a little of what then passed for news in his party by suggesting that it might in time supplant the Conservatives as the main opposition to Labour. He was slapped down by Paddy Ashdown, and most observers, including this one, concluded that this was an eccentricity too far Suddenly it doesn't look so eccentric. This week an ICM poll showed the Tories having dropped five points to 27 per cent since October and the Liberal Democrats gaining three to 23. If this movement was maintained, the parties would be level pegging by February and the Tories would be in third place by March. When, a few years ago, Charles Kennedy was languishing as the Liberal Democrats' agriculture spokesman, he made a little of what then passed for news in his party by suggesting that it might in time supplant the Conservatives as the main opposition to Labour. Nevertheless, you'd be hard put to imagine a gloomier moment for Iain Duncan Smith to rally his increasingly desperate party, as he tried to do at a meeting of the 1922 Committee in the House of Commons last night.