Brown will never be Prime Minister says Blair aide

Jonathan Powell, the premier’s chief of staff, was thrust to the centre of the new row over who will take over from Mr Blair, after claims that he had described the Chancellor as a figure from "a Shakespearean tragedy".

The Spectator magazine insisted Mr Powell had told its editor, Boris Johnson, the Tory front-bench MP, that Mr Brown was "like the guy who thinks he’s going to be king but never gets it".

Mr Powell is reported in this week’s edition of the magazine as adding: "He’s never going to be Prime Minister. You could never get a Scot as Prime Minister."

The conversation was said to have taken place when the pair met in Pall Mall, London, as they were both cycling.

The report will infuriate Mr Brown, whose aides had been delighted earlier this week when Mr Blair appeared to make his clearest statement yet that he wanted the Chancellor to succeed him after the next general election.

In a terse comment, Mr Brown’s spokesman said yesterday: "I think you should be ringing No10, because this is a story about Jonathan Powell. We’re getting on with the work we are doing."

Mr Blair’s official spokesman admitted that Mr Powell had met Mr Johnson on Pall Mall and said there had been some "light-hearted banter", but insisted Mr Powell never made the remark.

He went on: "Jonathan did not say it. There was some light-hearted banter on Pall Mall, but the last person Jonathan would confide his innermost thoughts to is Boris."

Significantly, Jack Straw refused to comment on the report at a Labour election press conference yesterday.

The Foreign Secretary, said to have moved closer to Mr Brown in recent months, also ducked a question about Mr Blair’s position.

Other Cabinet colleagues have insisted that the PM will serve a full third term if, as expected, Labour wins the next general election.

However, when asked about the chances of that happening, the Foreign Secretary said: "I only give odds on horse races."

Alistair Darling, the Scottish Secretary, was far more forthcoming - and even ruled himself out as a future Prime Minister, stating that Mr Blair was there for the long haul.

He told The Scotsman: "The thing people want to bear in mind is the Prime Minister is there. There is no contest. He is carrying on as Prime Minister for as long as he wants to, and I am happy with that."

Mr Darling dismissed the claims in the Spectator as "tittle tattle", and added: "I am sure it will boost Mr Johnson’s organ no end."

But Mr Johnson insisted later that the article was "100 per cent" accurate.

He said: "I’m afraid [Jonathan Powell’s] memory must be playing him false.

"I’m absolutely certain - I went away and wrote it down afterwards. I have absolutely no doubt whatsoever."

The conversation between Mr Powell and the Tory arts spokesman happened when the pair found themselves waiting at traffic lights.

Mr Johnson apparently raised the subject of relations between the Treasury and No10. Mr Powell was then reportedly pressed on why Mr Blair did not clear up any doubt about his future.

The magazine says Mr Powell replied: "I’ve advised him that he should be frank with people and tell them that, if elected, he can’t commit to serving a full fourth term."

If Mr Powell did assert that Mr Brown could not become Prime Minister because he is a Scot, he clearly has not read a history of the occupants of Downing Street. In the 70 years between 1894 and 1964, there have been seven Scottish prime ministers who covered a total of 25 years.