LONDON (Reuters) — Britain's new prime minister, Gordon Brown, appointed a trusted ally as finance minister and promoted a rising star to the key post of foreign minister in a wide-ranging government shakeup.Former environment minister David Miliband, 41, a reported critic of the Iraq war and once mooted as a leadership rival to Brown, was appointed foreign secretary, while loyal ally Alistair Darling, 53, succeeds Brown at the Treasury.

Brown, who switched from finance minister to prime minister on Wednesday after Blair resigned, acknowledged he must meet a demand for change from an electorate tired with 10 years of Labour Party rule, and draw a line under the unpopular Iraq war.

Analysts said the appointments of Darling and Miliband signalled no change in economic policy after Brown's successful decade-long tenure as finance minister, but a shift of tone in foreign affairs.

Brown has accepted responsibility for the cabinet decision to back the invasion of Iraq but will want to distance his government from Blair's approach, which was deeply unpopular among voters.

"The opportunities and challenges of the modern world require, in my view, a diplomacy that is patient as well as purposeful, which listens as well as leads," Miliband said.

Britain has been drawing down troop numbers in Iraq and now has about 5,500 in the south of the country. While Brown has pledged to stick to Britain's commitments in Iraq, there is speculation the withdrawal may accelerate.

"It's a clear indication that Brown wants to shift some of the style and focus of Blair's foreign policy," said David Mepham, head of the international unit at the Institute for Public Policy Research.

"Miliband wasn't closely associated with the decisions that were taken in the Iraq war. It's an asset when meeting foreign secretaries in other countries in getting people to focus instead on the problem of how to move things forward in Iraq."

Three British troops were killed by a roadside bomb in Basra on Wednesday, taking the number of British deaths in Iraq since the U.S.-led invasion in 2003 to 156.

Miliband was reportedly sceptical about the decision to go to war in Iraq and, according to media reports, voiced his dismay in cabinet at Blair's reluctance to call for an immediate ceasefire in last year's Lebanon war.

Former foreign secretary Jack Straw and a loyal Brown ally becomes justice minister, partly to tackle a crisis in Britain's prison service, while Ed Balls, Brown's right-hand man at the Treasury, became children, schools and families minister.

Another rising star, Douglas Alexander, become minister for international development, a key plank of Brown's foreign agenda, replacing Hilary Benn.

Benn was appointed environment minister, although it was not immediately clear whether that brief would include energy.

Top of Brown's domestic list were changes in schools and in the state-run National Health Service. Many Britons remain unhappy with public services, even though Blair's government pumped billions of pounds of extra funds into them.

Brown will also try to respond to demands for more affordable housing in a country that saw house prices nearly triple during Blair's decade in power. He is expected to make several significant policy announcements in the coming weeks. (Additional reporting by Katherine Baldwin, Sumeet Desai, Simon Rabinovitch and Sophie Walker)REUTERS