Unhappy anniversary: Brown battles to keep Henley deposit

As voters went to the polls in Boris Johnson's old seat, bookmakers said the party was odds-on to sink below five per cent in Henley, the threshold for a lost deposit.

Some were even speculating they could be beaten into fourth place by the Greens. The tense wait came as Labour began a period of soul-searching about Mr Brown's leadership, which is a year old tomorrow.

Foreign Secretary David Miliband, one of those seen as a possible successor, refused to confirm or deny his ambitions in an interview. Asked whether at some point he would have the desire to lead, he said: "I am not going there. I am utterly determined to be a very good Foreign Secretary in a Gordon Brown government. All other speculation is literally idle."

Although Mr Brown is said to be determined to ignore rather than celebrate his personal milestone, Mr Miliband's wide-ranging interview in the Independent fuelled talk of a beauty parade by potential successors.

It followed a series of interviews given by Work and Pensions Secretary James Purnell advertising his reformist credentials and claims that Children's Secretary Ed Balls is wooing grass roots and union supporters.

Mr Miliband argued that Labour could still win the battle of ideas so crucial in the political arena. "We are engaged in a very difficult project which is to renew Britain's most successful centre-Left project since 1945 and we are trying to do it in government," he said.

"I am convinced the tide of ideas has not turned against us, as Jim Callaghan knew it had before he lost in 1979," added Mr Miliband.

On Mr Brown's woes, Mr Miliband joked: "I am in the slightly odd position of predicting it would be like this."

He was referring to a BBC Question Time appearance, shortly before Mr Brown became Labour leader, in which he said people would soon be calling for Tony Blair to come back.

"I don't want to say 'I told you so', but it was always going to be tough to win a fourth election, defying political gravity. In addition leaders around the world are unpopular. I know that is not a very comforting point," he said.

After a successful first summer, Mr Brown's standing nosedived when he called off an autumn election, to accusations of dithering. Since then he has been hit by defeats in London and in the once-safe Crewe & Nantwich. He was also wrong-footed by the 10p tax rate row.

Although he was buoyed by success in the tight Commons vote over 42-day pre-charge detention for terror suspects, it was partly marred by claims he had to bribe rebels and Northern Ireland MPs to fall into line.

Former Labour deputy leader Roy Hattersley said Mr Brown needed to act fast to restore his personal reputation and win an election.

"Victory is more likely under Gordon Brown than under any other leader," he said, adding: "But the Prime Minister has to begin, and begin quickly, to re-establish his reputation as a politician of principle."

Lord Hattersley said "contrived" government initiatives would not be enough, saying Labour had been damaged by spin.

The New Labour guru Anthony Giddens said Mr Brown needed to show more of a "sense of purpose". Writing in the magazine Progress he said: "Labour needs a renewed sense of purpose, but also somewhere, somehow, a touch of inspiration too."