Gordon Brown, the UK chancellor, has launched his bid to succeed Tony Blair as leader of the Labour Party and Prime Minister in July 2007 by emphasising faith, hope and clarity about priorities – including open government, further health care reform, admission of the failures of policy in Iraq, and global vision.

“I do not believe politics is about celebrity”, declared Mr Brown, announcing his long-expected candidacy. “When you put yourself forward for leadership, the country has a right to know where you come from, what you believe in and what you want to achieve. My father was a minister of the church.”

The chancellor, a member of the Christian Socialist Movement, has long played up his Church of Scotland (Presbyterian) upbringing, but he has also pushed its values in an inclusive direction.

“I came into politics out of faith”, he declared. “Faith in people and their potential.” Less a Calvinist statement, more one of liberal optimism.

He explored his theme in a personal vein. “For me, my parents were – and their inspiration still is – my moral compass. The compass which has guided me through each stage of my life. They taught me the importance of integrity and decency, treating people fairly – and duty to others.”

Mr Brown said: “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.

“Government must be more open and more accountable to Parliament – for example in decisions about peace and war, in public appointments and in a new ministerial code of conduct.”

Mr Brown suggested that Britain could get its first written constitution under his premiership, saying: “We need a constitution that is clear about the rights and responsibilities of being a citizen in Britain today.”

On Iraq, Mr Brown forthrightly noted: “I accept that mistakes have been made.” He said he would be visiting Britain’s troops and “listening to what the government of Iraq says”.

Later, in a speech in Knebworth, in Hertfordshire, Mr Brown promised to create a “new kind of politics” in which the government “gives power away so that people in the community can have more power”.

He said the challenge facing the government was to “create a strong society” to go with Britain’s “strong economy” – indicating that while he has no intention of miving Labour back to the left, social justice concerns are still close to his heart.

His speeches also mentioned getting business fully signed up to a claimate change agenda, and continued work on the global vision of his past interventions about tackling poverty.

The major domestic plank of Brown’s pitch will be further health care reform, where continuation of a general market-style Blairite policy goal may be matched by a less dogmatic approach, say analysts.