Alistair Darling faced one of the toughest tests in politics today after being made Transport Secretary following Stephen Byers's shock resignation.
The smooth Scot, a close ally of Chancellor Gordon Brown, was appointed when he met Tony Blair in Downing Street this morning.
Paul Boateng became the first black Cabinet Minister as the Prime Minister reshaped his Government to fill the hole left by his close ally Mr Byers.
Mr Boateng was made Treasury Chief Secretary after Andrew Smith, who is currently on holiday, succeeded Mr Darling as Work and Pensions Secretary.
Former Downing Street aide David Miliband, who was only elected at the last General Election, seemed certain to take Mr Boateng's post of Treasury Financial Secretary.
The changes prompted a number of changes in junior ministerial ranks and, suprisingly, in the Civil Service..
Sir Richard Mottram, who was permanent secretary at the Department of Transport, and deeply involved in handling the Jo Moore affair moves to the same post at the Department of Work and Pensions. He has swapped jobs with Rachel Lomax.
Home Secretary David Blunkett revealed Lord Falconer, a close friend of Mr Blair, was moving to his department as part of the re–shuffle.
The peer had been responsible for the Dome which is due to be off–loaded in a deal expected to be announced in the next 48 hours. He now takes on the key task of reforming the criminal justice system, and will also be responsible for prisons and probation.
Former Home Office minister Mike O'Brien, who was sacked from the Government last year, becomes a Foreign Office minister with responsibility for the Middle East.
Deputy leader of the Commons Stephen Twigg becomes minister for education. He is replaced by the Foreign Office minister Ben Bradshaw.
Mr Blunkett also said Lord (Geoffrey) Filkin, currently transport spokesman in the Lords, was joining the Home Office as junior minister to Beverley Hughes, who moves within the department to take over immigration.
Hilary Benn moves to the Home Office from the Department for International Development to back up Lord Falconer on criminal justice, prisons and probation, added Mr Blunkett.
Mr Darling skilfully escaped the fall–out from the recent rows over pensions in his previous post.
Now he finds a dilapidated rail network, congested roads, problems at the newly–privatised air traffic control system and part–privatisation of the Tube competing for his attention.
However, his burden was somewhat lightened by the Prime Minister's decision to hand responsibility for local government and the regions back to his deputy John Prescott at the Cabinet Office.
A reshuffle had not been expected for around two months but Mr Byers' determination to go yesterday forced the Prime Minister to act – apparently against his wishes.
In a defiant statement at No 10, Mr Byers denied lying but said: "By remaining in office I damage the Government.
"Having worked for the Labour Party all my adult life, it is not easy to admit to that reality but I cannot and will not allow this to continue."
Liberal Democrat transport spokesman Don Foster said: "At last we have someone who can concentrate on delivering a safe, reliable and affordable public transport system.
"Alistair Darling must set out clearly his priorities for tackling the crisis in the transport system that the Government have failed to tackle in their first five years."
"It is essential that Mr Darling now takes the tough decisions that the current transport crisis demands. But he will need the full backing of all of the Cabinet, particularly the Prime Minister and the Treasury."
Shadow transport secretary Theresa May, who repeatedly called for Mr Byers' resignation, congratulated Mr Darling on his new appointment.
In a letter to the new Transport Secretary, Mrs May said she hoped he would address what she said were the five top priorities in his department.
These included adopting a "coherent and over–arching" transport strategy as soon as possible, resolving the Railtrack "mess", reversing levels of congestion, securing a future for the Tube and restoring air traffic control to "good health".
London's Transport Commissioner Bob Kiley said he hoped Mr Darling's appointment would signal a Government rethink of its Tube part privatisation.
Mr Boateng said he wanted to be judged on his performance and not by his colour. "First and foremost I am a Cabinet minister," he told Sky News.
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