By Brian Wheeler
BBC News Online political reporter
Fatherhood has mellowed Mr Brown
For a man famed for his dour demeanour, Chancellor Gordon Brown has been smiling a lot recently.
As he prepares to deliver his eighth budget, he knows he is in a unique position for a Labour chancellor.
The prospect of a ballooning national debt and sluggish tax receipts may be clouds on his horizon as he puts the finishing touches to Wednesday's speech.
But his economic growth forecasts - panned by some in the City last year as more than a little optimistic - have turned out to be broadly accurate.
And he remains the person most likely to succeed Tony Blair as leader of the Labour Party and prime minister.
He retains significant support within the party and, according to insiders, his potential rivals for the succession within the cabinet - with a handful of notable exceptions - accept his status as leader-in-waiting.
Marriage and fatherhood may also have contributed to the Chancellor's sunnier mood.
He remains a driven man, with a fearsome capacity for work. But there is less talk of "psychological flaws" in his character than there used to be, and the awkward questions about his private life have also ended.
Gordon Brown was born in Glasgow on 20 February 1951, the son of a Church of Scotland Minister in the small Fife town of Kirkcaldy.
At 12, he was canvassing for Labour and by his 20s he was a leading political activist in Scotland.
He achieved a first class degree in history from Edinburgh University, where he went on to complete a PhD.
His early career was spent lecturing, working in television and making a name for himself in the Scottish Labour Party.
His first attempt to enter Westminster, for Edinburgh South in 1979, was thwarted by the present Tory spokesman on foreign affairs, Michael Ancram.
The Chancellor still seems determined to play the waiting game
But in 1983, he took Dunfermline East, a new constituency including Rosyth naval base, pit villages and coastal towns.
Entering Westminster, he came to share an office with the newly elected MP for Sedgefield, Tony Blair.
Within four years, Mr Brown had gained his first frontbench post as shadow chief secretary to the Treasury.
He became shadow chancellor under John Smith's leadership in 1992.
After the death of leader John Smith in 1994 he stood aside, agreeing to give Tony Blair a clear run at the leadership in a famous meal at the Granita restaurant in Islington.
Still yearning to be PM?
The other part of the deal, that Mr Blair will one day stand down in favour of the chancellor, is the stuff of Westminster legend.
Mr Blair's supporters say such a deal never existed and endless newspaper columns - and even a television film - have been devoted to the rift.
But if his leadership ambitions were at least temporarily thwarted in 1994, Mr Brown continued his devotion to politics.
During the 1997 election campaign, he is said to have worked an average of 18 hours a day, six days a week after running on a treadmill for an hour each morning.
This dedication to his career was underlined by a comment by Mr Brown's former girlfriend of five years, Princess Marguerite of Romania, the eldest daughter of ex-King Michael of Romania, who said a relationship with him was "politics, politics, politics".
Mr Brown's relationship with his younger Downing Street neighbour remains the focus of intense scrutiny
If that was true then, Mr Brown, who married PR executive Sarah Macaulay in 2000, changed his perspective when the couple were hit by tragedy early in 2002.
Their daughter Jennifer died in Edinburgh Royal Infirmary, 10 days after being born seven weeks prematurely.
A year later, in October 2003, the couple had a son - John - an event which again gave the chancellor an opportunity to show his softer side.
In government, Mr Brown is undoubtedly Mr Blair's most able minister. As chancellor, he has won widespread praise for masterminding Britain's economic stability.
But Mr Brown's relationship with his younger Downing Street neighbour remains the focus of intense scrutiny.
According to some reports, the pair are barely on speaking terms. Others say they retain a good, if stormy, working relationship.
They are said to be split over the euro, with the chancellor less keen on entry than the prime minister (though they now seem to be agreed on one thing, that the UK joining the currency remains a long way off).
Mr Brown is also said to be against the further marketisation of public services.
But this did not prevent him from coming to the prime minister's rescue earlier this year, when he was facing a Commons defeat over university tuition fees.
Mr Brown reportedly reined in his supporters on the backbenches who were intent on wrecking the bill.
Anyone rubbing their hands in anticipation of a Brown leadership bid were, not for the first time, to be disappointed.
Recent press stories about Mr Brown being lined up for the top job at the International Monetary Fund (IMF) were seen by some as a sign that he is growing restless.
But others believe the Treasury allowed the story to run as a timely reminder of Mr Brown's stature on the international stage.
After nearly 10 years, the Chancellor still seems determined to play the waiting game.
And if some in Westminster are to be believed, the wait may soon be over.