Donald Macintyre's Sketch: Iain Duncan Smith head cheerleader as Tories roar on their hero

He could hardly contain his excitement at the announcement of a new 'national living wage'

Duncan Smith was known during his short tenure as Conservative leader as the Quiet Man. He was not quiet yesterday (PA)

A tsunami of joy – a hurricane of happiness – coursed through the quivering bodies of the Order Paper: brandishing, cheering, stomping, gesticulating Tory backbenchers.

And they were led, of course, by Iain Duncan Smith: fists clenched, maniacally grinning, less a prize fighter who has just put his opponent out for the count than Bez of Happy Mondays mid-number.

It was in preparation for this moment that IDS has always stood at the entrance to the commons chamber. He could never have performed his alarming, whole-body celebration of George Osborne’s announcement of a new “national living wage” while sitting down. Since it can’t have been a surprise, how did the Work and Pensions secretary react when he first heard about it? Turn cartwheels? Dance like a dervish on the Cabinet table?

Yes, after all the leaks, the Chancellor still had a rabbit to uncage – and in a reversal of the animal kingdom’s normal procedures, the rabbit had shot the fox! Ed Miliband had promised to raise the minimum wage by £8, Osborne was going to put it up –rebranded – to £9, by 2020. He even used the TUC’s own slogan: “Britain deserves a pay rise.”

Two rabbits, actually, since he pledged, finally, to keep Britain spending the Nato-prescribed 2 per cent of GDP on defence. This was not a time to seize the iPad and work out the small print. This was a time for wholesale obeisance to the magician who had made it happen – the leader in waiting. For the moment anyway.

Cleverly, Osborne performed his trick just after the grim passage about the “difficult and necessary” draconian cuts of £12bn in welfare, including his Chinese-echoing “two child policy”.

He proclaimed for the 892nd time “our long term economic plan is working ” before the ritual addendum: “But the greatest mistake… would be to think all our problems are solved. And about some of these he was candour itself. “We rank behind Puerto Rico and Namibia in the quality of our [road] network” he told startled MPs.

The opposition response to budgets is notoriously hard, but it showed. Faced with all this, a nonplussed Harriet Harman fell back on pre-cooked rhetoric which left alone the minimum wage announcement for too long. She was too winded even to claim Osborne had stolen it. And she didn’t really challenge the whopping cut in inheritance tax for the better off or his distinctly dodgy claim that it had been designed for the “very rich.” Even richer, presumably, than the 10 per cent of families who have had to pay it. And less rich than those with accountants to get them out of paying it altogether.

A pity, since inheritance tax has been championed since the 19th century by the likes of JS Mill and Jeremy Bentham. Even Friedrich Hayek, Margaret Thatcher’s economic guru, thought it could be used as “an instrument towards greater social mobility”. But what did they know?

Osborne also unveiled a dizzying litany of minor measures, including a raft of “prestigious” new Regius professorships, to celebrate the Queen’s 90th birthday. And if Boris was secretly aghast at Osborne’s near coronation, he didn’t show it, waving happily from the back of the chamber when the Chancellor announced repairs for the wartime RAF Fighter Command HQ in the Mayor’s constituency.

Boris was obliged to smile gamely at Osborne’s tease about the “dilapidated state” of the great anti-Heathrow champion’s “campaign bunker” – harking back to “when aeroplanes flew freely in the skies above West London”. Ouch. You don’t make jokes like that about your deadly rival unless you think you’re pulling well ahead.