The lengthy political and personal friendship of Alistair Darling and Gordon Brown has been tested to the full in recent weeks, as the Prime Minister, using his ten years inside the Treasury, has ruminated on measures that might help him and Labour out of the hole into which they have fallen.

When The Times reported in July that Mr Brown was drawing up his own “economic plan” the Treasury said it did not recognise the term. There have been rumours of big rows between the departments about what it should entail. The first fruits of the plan – which the Treasury has acknowledged only recently – will be seen this week.

No one denies that there have been tensions. But the temperature in the Brown household at No 10, and that of several Cabinet ministers, rose sharply on Saturday morning when they saw an interview that his neighbour Mr Darling had given to The Guardian while on holiday. His apocalyptic warning that conditions were “arguably the worst they’ve been in 60 years” contrasted heavily with statements from Mr Brown emphasising the “resilience” of the UK economy.

The Chancellor also raised eyebrows by warning that the public were “p***ed off” with Labour, and acknowledging that colleagues thought they could do his job better. Mr Darling, clearly in holiday mood, had said the kind of things he would normally never say in public.

It was dynamite. Mr Brown, after consulting allies, called Mr Darling and told him that he had to put the remarks in context. He must explain, as the Prime Minister had, that he had been talking about world conditions, adding that Britain was better placed to deal with this crisis than past governments.

Mr Brown and ministers would have preferred Mr Darling to “unsay” his words: they insist that conditions are in no way as bad as those of the 1970s, late 1980s and early 1990s. According to one Cabinet minister, Mr Darling had “handed it to the Tories on a plate”.

The Conservatives declared that the Chancellor had “let the cat out of the bag” and proved that government was divided at the top level.

Mr Darling duly began the damage-limitation exercise and Jack Straw, the Justice Secretary, did the round of television networks yesterday.

Treasury officials do not dispute that Mr Darling had used the words, but insist that he had been speaking about the international context. There had been no intention to cause problems for Mr Brown, they added, and Mr Darling’s reference to people wanting his job was a joke and not aimed at other members of the Cabinet, such as Ed Balls, the Schools Secretary.

There has also been speculation that Mr Brown could move David Miliband to the Treasury.

Mr Darling suggested there would be no reshuffle, words that appeared to suggest he had been told as much by Mr Brown. That, The Times was told authoritatively, was not the case.

There was speculation among ministers that Mr Darling had done the interview in the way he had because he feels that his job is threatened – but friends say that is not the case.

Speaking on The Andrew Marr Show, on BBC One, Mr Straw said that the Cabinet was completely in step. Mr Darling had been referring to the worldwide impact of the credit crunch and soaring food prices, Mr Straw emphasised. “The message from Gordon, from Alistair, from colleagues like myself has been the same,” the Justice Secretary said. “We have had a very good period of economic success, which has for sure provided us with a very serious platform to weather these storms.” Asked whether Mr Brown agreed with Mr Darling’s assessment of the economy, he replied: “Of course.”

Mr Straw denied that the atmosphere in the Labour Party was “febrile”.

He said: “It certainly got a bit lively in July, but people have had a period for reflection over the summer . . . There won’t be a leadership challenge from me or anybody else.” Mr Brown and Mr Darling will take every opportunity to show unity and appear together. Divisions between chancellors and prime ministers have been fatal.

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