Vince Cable was today appointed to succeed Lord Mandelson as Business Secretary and immediately went to his new office in Westminster to start work.
As Treasury spokesman for the Liberal Democrats, he won plaudits from all parties for his respected views on the state of the economy during the recession.
Dr Cable is that rare thing at Westminster - a senior politician whose reputation has been enhanced during the turmoil of the economic downturn.
While most ministers and MPs were accused - along with bankers and regulators - of failing to foresee the financial crisis, the Liberal Democrat deputy leader was credited with raising the alarm earlier than most.
He emerged from the wreckage of the recession as one of the most respected commentators on the economic decline.
Not the slickest of politicians, with his wispy white hair, Dr Cable nevertheless became a media favourite for talking incisively about exactly what was going wrong.
The economist became something of a Lib Dem pin-up, with rumours that even his leader, Nick Clegg, was envious of his popularity.
Some Lib Dems wondered whether Dr Cable should himself have been their choice as leader in 2007 after he took up the role on an acting basis and landed blow after blow on Gordon Brown at Prime Minister's Questions.
He reduced the Commons to gales of laughter, remarking on the premier's transformation, as events ran away from him, "from Stalin to Mr Bean".
But Dr Cable has shown little ambition for the top job and, as the party's Treasury spokesman, annoyed some of his frontbench colleagues in the past year.
Plans to introduce a "mansion tax" for the owners of the 250,000 most expensive homes were angrily received by Lib Dem MPs with constituencies in the South West in particular.
Other were angered that they had not been informed in advance about the proposals, which were instead sprung on the party at its most recent autumn conference.
The scheme was later scaled back after, as Mr Clegg put it, they had been forced to "do some homework".
Dr Cable, who turned 67 on Sunday, was relatively advanced in years when he became an MP, for Twickenham, in 1997.
He was then 53, with an impressive CV in the private sector built on a Cambridge degree and a PhD in economics from Glasgow University.
By the time he was elected to the Commons, he had risen to chief economist at oil giant Shell.
Away from the worlds of business, finance and politics, Dr Cable is known to be a keen ballroom dancer.
He has a "serious ambition" to appear on television show Strictly Come Dancing, he once revealed.
As Secretary of State for Business, Innovation and Skills he will have a series of issues in his in-tray, including energy security, job creation, promotion of trade and industry as well on-going debates about the future of institutions such as the Royal Mail.
David Frost, director general of the British Chambers of Commerce, said: "Vince Cable understands business and is popular with many small and medium-sized companies.
"His work as the Liberal Democrats' shadow chancellor means that he knows where the UK fits within a global context and the important role the private sector will play in driving future job creation and economic growth.
"His relentless focus on making sure that the banks lend to viable, credit-worthy businesses will be a critical part of his new position. However, with reform of the banking system on its way, he must ensure that these reforms do not lead to an upheaval for businesses."