This story may be a lesson in the virtues of vitamin C and blackcurrants. When he was eight Michael Portillo was the Ribena Kid. Now he is 40, the youngest member of the Cabinet, and, they say, the next Prime Minister but one. Does he remember the slogan in the television ad - 'Every day a little older, a little wiser, a little stronger'?

If any of the laws of public life hold true, Michael Portillo should be due a great fall. He was 33-to-1 outsider in the William Hill Conservative leadership odds nine months ago. Now he is 5-to-1 third favourite, behind Kenneth Clarke and Michael Howard. That's like going from being Princess Michael of Kent to being Prince William. If everything continues as planned, this man will be king.

At last week's Conservative conference they knew this. Last Thursday the Chancellor replied to the economics debate, and gave Portillo, his man in charge of the spending review in advance of next month's Budget, exactly the sort of praise a man with that role needs: 'the toughest chief secretary I have ever worked with'. Portillo, looking absurdly young and gawky, gave a self-deprecating smirk. The audience approved.

In the evening Portillo gave an address under the title 'The Blue Horizon' to a packed fringe meeting. It was a remarkable speech for October in Blackpool, not least in that it dared a bit of vision. It was good to hear a Conservative admit 'we are in a dreadful hole' - even if he then attributed the remark to his boss. But most intriguing was the audience. How often do chief secretaries to the Treasury find themselves mobbed (decorously) by autograph hunters?

'I'm very impressed: I think he's super]' said Lynn Wain, a delegate from Brentwood. 'He speaks directly and he's cerebral. It was the best speech I've heard.' Portillo, overhearing this, had the grace to blush slightly, and then submitted willingly to being photographed with Ms Wain. Elsewhere in the room, a perfectly groomed Conservative Student, Nicholas Hill, gave his verdict: 'Intellectual power, honesty and charisma. Portillo has the edge.' A straw poll produced no one in whose blue horizon Michael Portillo, 40, does not loom large.

Portillo sees himself there, too. At the meeting he talked of the pre-Budget spending round process and his 'revolutionary' idea of deciding the overall spending limits before listening to each department, thus avoiding the over-bidding and haggling that normally characterise the system. 'Revolution' is a word Portillo likes. Small politicians create policy. Big ones rearrange the landscape. And he has never wanted to be anything but the biggest.

Portillo's rise has been astonishingly swift: he was a cabinet minister eight years after entering the Commons. The son of a Spanish poet and minister in the republican government overthrown by Franco, and a socialist Scottish teacher, he had a poster of Harold Wilson on his study door at Harrow County Grammar School. But he was not active in politics at Peterhouse, Cambridge.

Conservatism was thrust upon him a year after he left. Languishing as a management trainee for an air freight company, he asked his tutor, the right-wing Conservative thinker Maurice Cowling, to find him a happier job. He ended up under Chris Patten in the Conservative Central Office research department. At 26 he was on Margaret Thatcher's staff for the 1979 general election, where he impressed her and she flattered him. He impressed ministers as a special adviser at various departments - in his memoirs Nigel Lawson calls him 'the outstanding member of his generation in the House' - and was then taken on by Cecil Parkinson at the DTI. He was the 'detective' who drove Cecil Parkinson away from the 1983 Conservative conference - the first but not the last occasion that he has seen his bosses' careers crumble with spectacular speed.

As junior minister at the DHSS he watched John Moore reduced from being Mrs Thatcher's heir apparent to, in Alan Clark's phrase, 'a husk, cut down so young', in a matter of months. He has been aware ever since, friends say, of the dangers of over-billing.

After two years as Minister of State at Transport, he was moved to environment and given the most poisoned of chalices: defender of the poll tax. He took on the job with gusto, telling the 1990 Conservative conference that it was an 'election winner'.

Should he have gone down with the tax? Michael Heseltine insisted that he be kept on to help prepare the council tax because, by then, there was no one more expert at local government financing. Heseltine called him the AA man: Heseltine might not know, but 'I know a man who does'.

This sort of praise - of his intelligence, diligence, loyalty - is typical of Portillo's former bosses. He will need more than those qualities to go the final mile. He knows he needs a philosophy that builds on and is at least as persuasive as Mrs Thatcher's. This is already being talked up: 'He is,' insists an influential friend, 'not a politician, but a statesman. He means what he says.'

The philosophy will be based on Portillo's core credos: anti-statism, not least the Euro-state (friends says he would resign over fundamental issues like re-entry to the ERM), the need to restore the individual's sense of moral responsibility - a grown-up version of the libertarian theology that inspired the young far-right of the early Eighties. There's no reason to think Portillo has done more than draw a discreet curtain round these beliefs: its chief exponents, people like the MPs Michael Forsyth, Neil Hamilton and the right-wing Conservative thinker David Hart, remain his closest allies and friends.

But while Portillo does the groundwork of what he and his friends believe can be a Conservative ideology for the next century, you suspect he may be missing a vital point. What is there here for the voter but a picture of man with a wife earning in excess of 200,000 a year through her public relations consultancy, who's never lived a moment in any sort of real world? The ideas put forward in his Blackpool speech - of the 'amoral state' and the need to reverse the effects of a benefits system that pays people to forgo a sense of moral responsibility - are intriguing, even seductive. But there are still those in his own party who worry about Portillo's 'undeserving poor', or even this year's favourite villain, the teenage single mum.

So, some might ask, how do you stop the rise and rise of Michael Portillo? There's word that John Major might make him Conservative Party chairman next year to slow him down, just as Mrs Thatcher did Kenneth Baker. Perhaps he should settle for 'next Prime Minister but two' - using an intervening Labour administration to gain the experience of business and the real world he needs.

At the moment his base is too narrow, he's too No Turning Back Group (though the far-right MPs are reportedly disenchanted recently by their favourite son's flirtation with tax rises), and he needs more friends. Last year's intake of new MPs each received a note of welcome from M Portillo. He could be too clever. It's suggested that the cruellest possible fate for Portillo would be to be the brains behind the next Conservative revolution; Keith Joseph to the next Mrs Thatcher. 'Better, though, to be too bright than too thick,' says one friend. 'The party has had enough of that.'

'Every day a little stronger' There is no need to rush. An old ally of Mrs Thatcher who has observed Portillo for 20 years says: 'It's difficult to see, unless he makes an arse of himself, how things could go wrong.' It is hard not to agree.

(Photograph omitted)