Gordon Brown is reputed to be a workaholic, so he is keen to prove that he has a number of interests beyond politics. His entry in Who's Who lists golf, tennis and reading, and he has just returned from a week's holiday in Portugal, where, indeed, he played a lot of tennis. Reading? On the table between us was a heavyweight trio of books: The Culture of Complaint by Robert Hughes; The Moral Sense by James Q Wilson and The Fifties by David Halberstam.

The bookshelves in his office groan under the weight of massed Hansards, enlivened only by a shiny yellow model of a fork-lift truck. There are no family snapshots, no signed or press photographs. His desk, too, is a serious working space. Two halogen lights beam relentlessly down on to the word-processor. To its right are a telephone and a fax machine. Nothing here to distract from the practice of politics and the pursuit of Labour's overriding goal: victory at the next general election.

If it comes, it will not sweep Gordon Brown into the top job, although he was widely regarded as Neil Kinnock's heir presumptive and, for the first year at least, John Smith's as well. Brown does not admit to being disappointed; too canny by far. 'There was never any chance that Tony Blair and I would stand against each other - we'd never vie with one another simply out of personal ambition. Our main aim is to work as a team and change the country for the better.'

But couldn't he himself have headed that team? 'I had to take a view of what was best, and I did. The Labour Party has come through this united; Tony Blair has established a clear identity with the public, and I feel part of a team.' But he must have regrets? 'Sometimes personal ambition has to come second.'

What he won't say is that personal tensions between certain members of the Shadow Cabinet (Robin Cook is widely said to dislike Brown; Brown to be at odds with Prescott) - meant that Blair was the only leader with whom all three corners of the top triangle could work.

Now, he says, 'we're a pretty good team: whereas the Tories are fragmented and in disarray, all fighting each other'. Has he, then, abandoned any ambition to be Prime Minister? He smiles. 'No politician, if he's honest, will ever say that.'

Politics has been Gordon Brown's passion since he was a schoolboy. Born in Kirkcaldy (he corrects my pronunciation: 'Kircoddy') in 1951, he is the middle son of a minister in the Church of Scotland. He grew up in the centre of the community: 'There was always somebody dying, begging, or being baptised. Our family life was a mixture of social work and theology. Calvinism is quite a frightening, and a very private, religion. I came to believe in the smallness of people in regard to some great duty.' Yet his father was not, Brown insists, a dour or authoritarian figure.

In the early Sixties, Fife experimented with a scheme by which clever children were pushed into university a year early. Brown sat his O-levels at 14, his 'Highers' at 15 and went to Edinburgh University to read history aged 16.

In his first week there, it was discovered that a rugger accident earlier that year ('I got to the bottom of the scrum and was kicked to pieces') had resulted in a detached retina. It was operated on, but too late. Despite lying flat and immobile for two weeks, he lost the sight of his left eye, and for years the right was at risk as well. He dismisses the idea that he might easily have been blinded. 'It was not being able to play rugby that annoyed me more than anything. I think if you're physically fit you're mentally much sharper. The life of an MP is ridiculous in terms of the hours you're forced to work - voting at midnight or 2am is routine - so an 18-hour day is normal. In addition, most Scottish MPs actually live in their constituencies and travel up and down each week.'

Gordon Brown's home is in North Queensferry, Fife - the village at the north end of the Forth Bridge, at the very southern edge of his constituency. A large, detached house, it sits on a hill with a few others commanding splendid views straight down the Firth of Forth. Edinburgh and its castle are away to one side, the North Sea in the far distance. Also visible are the dwindling numbers of naval ships coming to Rosyth dockyard. These houses, built between 1890 and 1914 with an eye to rich Edinburgh commuters, are plain and indeed rather ugly, but big enough for a large Victorian family with servants.

Gordon Brown lives alone. His private life - like that of any man unmarried by his forties - is a matter for speculation; but not a shred of scandal adheres to his name. It has been 'linked', in Hello] parlance, with that of Princess Margarita of Romania, which probably hasn't done him any harm, and with that of a Scottish advocate and a television presenter.

I ask the standard question. He parries fluently: 'Marriage? It's just something that hasn't happened. There's no decision on my part not to be married . . . but I've got loads of friends, and spend a lot of time on films, music, theatre, sports, so my time is not restricted to politics.'

After four years at Edinburgh University, culminating in a brilliant First in history, Brown stayed on to do a PhD and was elected Rector at the age of 21: his first heady experience of confronting the masters. He was a lecturer in politics at Glasgow from 1976 to 1980 and then switched to journalism. He worked for Scottish television ('very good experience') covering sports, current affairs and the arts, before winning the safe Labour seat of Dunfermline East in 1983. Since then his rise through the hierarchy of the Labour Party has been relentless, interrupted only now by his tactical decision to let Tony Blair step into the spotlight. Brown remains his closest supporter, and a certainty for Chancellor of the Exchequer if Labour wins the next election. He is convinced it will, and that the electorate shares his rage and disillusionment with Conservative policies and people.

He is particularly enraged by the way in which some former ministers have apparently benefited personally from their privatising policies while in office. He ticks them off: 'Norman Tebbit privatised British Telecom: and now he's on the board. Peter Walker privatised British Gas: and now he's on the board. Lord Young presided over the formation of Cable & Wireless: and now he's chairman, on nearly pounds 1m a year. Norman Fowler privatised National Freight - and is now sitting on the board. It's a continuous succession from Cabinet room to boardroom.

'Not only that: there are all those electricity and water millionaires who made money simply by being there when the public utilities were privatised, not by being any more efficient or productive . . . while the pensioners, next winter, are having to pay VAT on fuel. The sense of fair play got lost in the Eighties; but in the end, people do believe that society should be run on principles of fair dealing.

'People still think Labour threatens their aspirations: they must understand that paying VAT on fuel penalises more people unfairly. I have to convince people that we don't look for increased opportunities to tax them.

'After that our priority is education. A modern economy depends on people's skills and talents. Everything else can be bought on the global market - raw materials, capital, technological advance - but the key is the least mobile factor: the skills of our own workforce. We must make a huge leap in educational standards. It has to be a national crusade. Our mission must be to become the best-educated country in the West.'

In the flesh, Gordon Brown speaks with a passion that is somehow absent from his lacklustre television manner. He has a marvellous politician's voice, with its classless Scottish burr, a strong face and intense gaze that speak of real convictions deeply held; but the soundbite does him a disservice.

He remains intensely Scottish, unflinching in his commitment to a Scottish parliament. 'Legislation for that will begin immediately Labour comes to power. People in Scotland and Wales want devolution. The Secretary of State for Scotland and 10,000 civil servants in the Scottish Office are responsible for health, education, transport, law, social services - one man with one Question Time every few weeks should not be making decisions which could and should be made by more democratic means.'

Would he swap the job of Chancellor of the Exchequer to lead Labour in a Scottish Assembly?

'I'm at Westminster, and I have a job to do here. I hope the Scottish parliament will be up and running pretty quickly, but I can't just switch jobs or parliaments. I have to be consistent.'

He goes on: 'Fifteen years in opposition have made us think very carefully. The most important thing now is to have a welfare state and health service that people believe in. It must be reformed and modernised, not dismantled. A Labour party in government would offer economic, employment and educational opportunities for everyone.'

Who could disagree with that - but is it possible?

'Yes]' he says, with the utmost vehemence.

Gordon Brown is two years older than Tony Blair, and remains his closest supporter and friend. If Labour is facing a spell in government, there is no reason to suppose that Blair will relinquish the top job. But who would ever have thought Jim Callaghan, four years older than Harold Wilson, would reach the premiership? Yet he did. Politics is the art of the possible and the history of the unexpected. Gordon Brown's crucial role in carving out a new economic strategy for an ideologically rejuvenated Labour Party could yet see him reach the pinnacle of power.

He has the politician's ability to find a common acquaintance and it didn't take him long to discover that we both knew John McGrath, founder and director of the 7:84 Theatre Company, of which Brown is a board member. Bonded - as he had intended - by this happy coincidence, we went on to discuss little theatre groups; the Edinburgh Festival, with particular reference to books (and here he made graceful reference to one of mine); the many films currently being shot in Scotland - and this cultural diversion ended with the information that he is also on the board of the Edinburgh Film Festival.

Gordon Brown's life is not devoted entirely to politics. But nearly.

(Photographs omitted)