I'll try hard to be humble says Brown

• PM-in-waiting pledges to end spin

• Blair finally endorses Brown to succeed him

Gordon Brown has offered a decisive break with the failures of the Blair era by promising a more humble government dedicated to rebuilding trust with the British people.

He consigned to the political wasteheap the outgoing Prime Minister's obsession with spin, as well as the arrogance and the culture of celebrity of the past decade.

Liberated by Tony Blair's resignation, the Chancellor stepped into the limelight to claim the Labour leadership with a passionate statement of his beliefs.

Scroll down for more...

For the first time the public heard Mr Brown set out in detail the ambition that drives him and his hopes for a "new government".

He held out the prospect of far-reaching changes in both style and substance, with an end to the media-management that marked the Blair administration.

On Iraq he offered a new direction, promising to focus on economic development and political reconciliation in coming months. He confirmed he would visit the Middle East within weeks.

And he signalled a major shift in the way Britain is run that would put Parliament in the driving seat and could lead eventually to a written constitution.

Mr Brown's speech was the opening salvo in what will be six weeks of announcements and initiatives as he tries to break free of his predecessor's legacy.

With the long-awaited campaign at last underway, he appeared at ease as he toured a string of marginals in the southeast in what his aides said was a signal that he is ready to take on David Cameron and the Tories.

But he faces an uphill struggle to revive Labour's flagging fortunes amid polls that put Mr Cameron 10 points ahead of a party that is financially strapped and still reeling from its drubbing in last week's local elections.

Mr Brown left no doubt that his aim is to repair the damage done by scandals, sleaze and a presidential style of government that put a small coterie of advisers ahead of Parliament.

In what amounted to a thinly-veiled repudiation of how Mr Blair operated, he announced: "The way we govern must change."

He went on: "I want to lead a government humble enough to know its place - where I will always strive to be - on people's side."

He wanted to lead Labour and "a new government", he said: "For me this starts with governing in a different way.

"Just as my first act as Chancellor was to give away power to the Bank of England to restore trust in economic policy, so one of my first acts as Prime Minister would be to restore power to Parliament in order to build the trust of the British people in our democracy."

Sporting a new haircut, and with his wife Sarah alongside, Mr Brown looked confident as he launched into a personal declaration that has been more than 10 years in preparation.

He cited the role-model of his church minister father who provided his "moral compass" and his experience as a father of young children to explain why he is so determined to succeed Mr Blair.

"Let me set out simply my core belief," he said. "The Britain I believe in is a Britain of fairness and opportunity for all. If you work hard you're better off. If you save, you're rewarded. If you play by the rules, we'll stand by you."

Mr Brown made plain that he would change the way the Government operates, by putting civil servants ahead of political appointees in the Downing Street operation.

He promised to spend the next weeks travelling the country to "listen" to voters, as a prelude to a government that would learn from its mistakes. His aides said the campaign would be a chance for the voters to find out more about the "real Gordon".

"I have never believed presentation should be a substitute for policy. I do not believe politics is about celebrity," he told an audience of hand-picked young activists at the London launch of his "Gordon Brown for Britain" campaign.

As if to prove his point, a succession presentational gaffes dogged a day of campaigning around London. Viewers of Mr Brown's televised statement struggled to see his face hidden behind a badly-placed teleprompter screen.

But there was no escaping the novelty of an appearance by the Chancellor in which for the first time he appeared comfortable fielding a succession of questions on a wide range of current issues, from Europe to health.

The launch of a campaign that many expect will see him elected without facing a contest coincided with endorsements from a number of key Labour players who until now have led bitter opposition to the Chancellor.

Campaign manager Jack Straw is trying to secure a maximum number of nominations from Labour's 352 MPs by next Thursday when nominations close. He is believed to have at least 200 so far.

Former Cabinet minister Alan Milburn and Stephen Byers issued statements of support, along with John Prescott and Tony Blair, who offered what sounded like grudging backing.

The moves appeared to have been co-ordinated to unite the party, with Mr Brown's installation at Number 10 now regarded as inevitable.

The two candidates from Labour's Left - ex-environment minister Michael Meacher and John McDonnell - are having difficulty gaining the nominations from 44 MPs they need for a place on the ballot.

They have taken up a challenge from Mr Brown to debate with him tomorrow SUN at a Fabian society event in London.

Mr Prescott, who is standing down as deputy leader, described Mr Brown as "head and shoulders" above any other potential candidate.

Mr Milburn, the former Health Secretary once talked of as a challenger for the leadership, said in a statement: "It is important that the whole of the party now unites around Gordon.

"I do so in the hope and expectation that his leadership will rebuild the popular coalition of support that brought us three election victories under Tony Blair and can win us a fourth under Gordon Brown."