Sir Andrew Turnbull, a former senior colleague at the Exchequer, Britain’s treasury department, once described Mr. Brown’s management style as Stalinist. Mr. Brown’s adversaries depict him as brusque and reclusive. To some, he resembles a dark prince who has waited a decade for his throne only to see his inheritance devalued by an unpopular war in Iraq, hints of economic troubles and a loss of trust in his party.  “His dread must be that he will finally get to sup from the chalice only to find that it is poisoned,” Andrew Rawnsley wrote in a commentary in The Observer.  Mr. Brown has promised a switch from the celebrity overtones of the Blair era to a more stalwart aura.  “I think we’re moving from this period when celebrity matters, when people have become famous for being famous,” Mr. Brown said in an interview published in The Guardian last month. “I’ve somehow got more faith in the essential decency of the British people: they want to talk about big and important issues in a way that does justice to them.”  In many political successions, the new arrival can simply blame the predecessor for an inheritance of woes. But that is not the case here. Since Labor came to power in 1997, Mr. Blair and Mr. Brown have almost been partners. Mr. Brown was at the prime minister’s side through three election victories and, as chancellor of the Exchequer, wielded enormous power over swelling public spending and soaring tax bills.  When he takes power in late June or early July, thus, he will be under pressure to signal a break with the past to shed the unpopularity Mr. Blair brought on himself and his party from the Iraq war, and steel his followers for what could be a closely fought general election, possibly within two years.  The style will certainly be different. Mr. Blair is comfortable speaking off the cuff, for instance. As Mr. Brown addresses an audience, his hands move constantly to bring any errant pages of his address into line, as if he seeks to marshal an unruly army.  His critics note that when confronted by trouble, he has a knack for withdrawing out of sight — as after last week’s regional elections, in which Labor lost heavily, particularly in Scotland, Mr. Brown’s home turf, despite his campaigning.  In the House of Commons on Wednesday, indeed, the Conservatives’ Mr. Cameron taunted Mr. Brown to his face across the green leather benches for apparently disappearing in the face of trouble.  “Everybody knows who the next Labor leader is, and thank God he’s got out of his black limo and come to the Commons,” Mr. Cameron said, adding that with Mr. Blair and his allies all but gone, Britain was living under “a government of the living dead.”  Mr. Brown’s claim on power dates to a never-confirmed deal with Mr. Blair in 1994, struck over dinner at a restaurant called Granita in the Islington neighborhood of London. Initially, Mr. Brown was expecting a transfer of power relatively soon in Labor’s ascendancy. But election followed election and the deal gave way to a poorly disguised rivalry that sometimes, as happened last summer, spilled into what Mr. Blair’s followers called a coup attempt by Mr. Brown’s followers.  Finally, in September 2004, Mr. Blair said he would not fight a fourth election but would serve a full third term after the 2005 balloting. In the British political calendar, that could have kept him in office until 2010.  After last year’s insurrection, the prime minister abandoned that hope, announcing in September that he would be out within a year. That transfer is now set to begin. But it is coming much later than Mr. Brown might have wished.  He is inheriting a party midway through its third term with its campaign coffers low after a financing scandal, and its membership reduced. Most of the heavyweight Labor politicians who might have challenged Mr. Brown have withdrawn from the fray.  In practical terms, Mr. Brown’s “in” box will include, predominantly, the shaping of his foreign policies in Iraq and Afghanistan, where British troops are taking steady losses, and, closer to home, the decline of Labor Party power, particularly in his Scottish fief, where the separatist Scottish National Party emerged in last week’s voting as the biggest grouping, ending five decades of Labor dominance.  Mr. Brown has hinted that he will seek to move away from Mr. Blair’s militarism in the Muslim world toward a “hearts and minds” battle against radical Islam. He is expected to seek a new tone in relations with the United States, to escape the jibe that haunted Mr. Blair, of being President Bush’s “poodle.”  At home, Mr. Brown has made it clear that he will oppose any moves toward Scottish independence from Britain.  Perhaps the biggest challenge, some argue, is to restore trust in politicians and to make a break with the past. “The biggest issue is distinguishing himself from Tony Blair,” said Timothy Garton Ash, a professor of modern history at Oxford University.  But mistrust of the Blair government over Iraq might, perversely, offer an advantage to Mr. Brown.  “I think he is seen as a somewhat more solid, son-of-the-manse clergyman’s son, giving it to you straight, to the point of being boring,” Professor Garton Ash said in a telephone interview. “He’s not regarded as a prince of spin or a liar.”  A version of this article appears in print on , on Page A4 of the New York edition with the headline: Scot With Baggage Readies Move Into the Leader’s Role. Order Reprints| Today's Paper|Subscribe
Britons seem set to trade the Great Communicator for the Great Puzzle in Prime Minister Tony Blair’s likely successor, James Gordon Brown.