As he rose Lazarus-like from the political dead to rescue Britain's banks, Gordon Brown was lauded as a "magician" by Germany, copied unashamedly by President Bush - and even praised as a genius by the new Nobel economics laureate.

Critics mocked him, of course, as being on a one-man mission to save the world - but Mr Brown brushed their assertions aside with a gruff wave of the hand.

Until now, that is. At today's Prime Minister's Questions - for just one second - Mr Brown let the cat out of the bag.

Faced by David Cameron's first question, on why his multi-billion-pound banks bailout had failed to filter down to the taxpayer, the PM replied: "We not only saved the world..."

Cue Commons hysteria. Mr Brown stuttered, stumbled, desperately tried to correct himself - but amid the juvenile surroundings of the House of Commons, it was all far too little, too late. Tory and Lib Dem MPs jeered, yelled, and made all manner of other noises, while the PM attempted something resembling a smile.

Battling through the noise after a long pause, a decidedly crimson Superman attempted to clarify what he meant. "We not only worked with other countries to save the world's banking system..." he said, to shouts of "Ah!" from MPs, before accusing the Tories of doing nothing in the face of the recession.

When Mr Cameron rose to his feet again, he couldn't resist the first of several gibes. "Well, it's now on the record..." he said, causing more hysteria. "He is so busy talking about saving the world, he has forgotten about the businesses in the country that he's meant to be governing."

Completely ignoring the Tory leader, the Prime Minister launched into an attack on Mr Cameron for rejecting his prized fiscal stimulus - the plan to borrow record amounts of money in order to invest more in the economy. "The opposition is still clinging to the failed economic policies of the 80s!" he bellowed.

Undeterred by the sense-of-humour bypass, Mr Cameron poked fun with another gibe and accused the Government of making Britain "near bankrupt" with borrowing and setting the country up for huge tax rises in future.

With the red face of embarrassment now replaced by the crimson of anger, the PM reverted to one of his favourite postures - a schoolmaster handing down a lecture to the smart-alec at the back of the class. "I am sorry to have to teach him about what an economy is about!" he shouted.

As both men sat down after their duel, MPs in the Commons settled in their seats - assuming their fun and games was over.

But then up stepped Alan Simpson, a famously rebellious Labour backbencher. "It is quite nice to have a Prime Minister who would save the world when we are faced with an Opposition who would barely save face," he said.

Cue huge cheers from the Labour benches - and not without a tinge of surprise mixed in. Mr Simpson is one of Labour's most prolific left-wing rebels and his criticisms of the PM are usually more vicious than those of Mr Cameron.

With such new-found friends, Mr Brown's now-official bid to save the world must be having some impact.

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