Gordon Brown is designated Britain's new prime minister as Tony Blair steps down from office. And although Brown has been at the heart of British politics for the last decade, many people still are not sure what to expect from him as a leader. From London, Mandy Clark has this profile.

He has been a key player in British politics for the past 10 years. As finance minister, he has been in charge of the country's economy. But Gordon Brown, the man, remains something of an enigma.

Born near Glasgow, Scotland, he grew up as the son of a protestant minister.

He joined the left-leaning Labor Party as a teenager, and headed to Edinburgh University to study history. There he served on the student council and earned a doctorate.

Brown won a seat in parliament in 1983, and shared an office with another newly elected Labor politician -- Tony Blair.

Together they pulled the party out of the political wilderness, says political biographer Anthony Seldon.

"It's an extraordinary relationship, there has been none like it in British politics in the last 100 years,? says Seldon.  ?They were powerfully creative, they together established the Labor Party as the force in British politics.  They made it into a successful government, they worked very closely together but then they fell out so there is very strong love between them and very strong hatred."

In the early years, Brown stayed in the background managing the economy, while Mr. Blair took the limelight. Political folklore says they had an agreement that Mr. Blair would hand over power after five years. But when the time came Mr. Blair refused and their friendship fractured.

In 2000, the workaholic Brown married. And the birth of two sons has helped soften his image.

Yet, the economy is his trump card. The red suitcase, known as the budget box, holds the finance minister's annual government spending plans. Both friend and foe credit him for the country's economic stability.

But being famous for fiscal prudence has left him with an image of a serious, sober Scotsman.

"He certainly doesn't have the charisma of Tony Blair, but I don't think that is necessarily a bad thing," said one citizen.  "I think that we are perhaps a bit sick of that kind of presentation politics, I think if he is someone who gets on with the job then that's a good thing and it's maybe time for that now."

"He has to prove himself in a number of issues I think and certainly how he handles the war, the Iraq situation, how that goes, may be a big swing in popularity either towards him or against him," said another.

Brown names security and terrorism as major international challenges, and many say Iraq will be his greatest challenge. He admits mistakes have been made there.

His other great battle will be taking on opposition leader David Cameron. Some consider Cameron Mr. Blair's political heir, emulating the youth and charisma of the prime minister's early years.

Michael Brown, a former Conservative politician, says the next election battle will be hard fought.

"The question on how the battle, the new battle between Gordon Brown on the one hand and David Cameron on the other, the Tory leader, is going to go -- not a single journalist, not a single member of parliament is able to put any money on who is going to win," he says.  "It is going to be one of the most open political races that we have had in this country for the last 15 years."

To compete, Brown is trying to shed his dour image -- though he maintains what he may lack in style, he makes up for in substance.

By the time the elections are called, he will have been prime minister for two years. It will then be the voters turn to decide if they like what they have seen from this private and prudent politician.