Luckily for Mr Brown, every British voter is aware of his impressive achievements in the past and his even grander ambitions for the future. His image as a serious contender for Prime Minister is too deeply ingrained in the public mind to be obliterated by one poor performance. Even more luckily, very few people bother to watch the PreBudget Report. But very unluckily for the Chancellor, this year’s PBR could well have been an exception. Normally the public pays very little attention to parliamentary set-pieces, but this speech was supposed to be different. Yesterday Mr Brown was expected to offer British voters their first clear glimpses of a Prime Minister-in-waiting — an imaginative and dynamic politician, all of whose natural energies had been channelled by fate into the one narrow stream of economics, but were now about to break out.

Why, then, did the PBR tell us absolutely nothing new about Mr Brown’s policies or ideas? Why did the Chancellor say so little of substance, beyond his standard litany of statistics about the economy’s creditable, but unspectacular, performance and his usual promises about meeting fiscal targets? Why were his few more specific announcements, in policy areas such as education and climate change, mostly just repetitions or small extensions of previous plans? And why did he say nothing at all about the issues that now seem to matter most to British voters — crime and security, health and foreign affairs?

One possibility is that the Chancellor simply did not want to make much impression with this PBR. He needed, by law, to go through the motions of announcing various forecasts and statistics, but maybe he never wanted to talk about his broader agenda in this speech. This explanation can be dismissed out of hand. The Treasury could easily have dampened expectations about the policy content of this PBR by indicating in advance that this would be a purely technical speech. But, on the contrary, speculation was encouraged that this PBR, like many previous Budget speeches, would offer important clues about where Mr Brown wanted to take Britain and how his leadership might differ from that of Tony Blair.

But if Mr Brown was trying to convey something of substance yesterday, what on earth could it have been? There seem to be two plausible answers. The first is that Mr Brown is so proud of his economic record — and has been so deeply involved in all areas of policy formulation under Mr Blair — that he really has very little new to say. His strategy when he becomes Prime Minister will therefore be to stick with present policies on everything from health and education to crime and Iraq. His hopes of reviving the popularity of Labour and winning the next general election would therefore depend on promises of continuity and economic competence. Would a slogan of “Five More Years”, backed up by national rejoicing at Mr Brown’s elevation to his rightful position as Prime Minister, be sufficient to bring disillusioned Labour voters back to the polling booths? It seems unlikely that even Mr Brown believes this, so we must look for another answer.

The second possibility is that Mr Brown genuinely considers that the meagre initiatives he announced yesterday are exciting new ideas. Take climate change and education, two of the top priorities for Mr Brown. On climate change, his big contribution has been to commission the impressive report published last month by Sir Nicholas Stern, the Treasury’s former chief economist. Contrary to expectations, however, Mr Brown failed to implement any of the major recommendations of Sir Nicholas in yesterday’s PBR, refusing even to reintroduce the fuel-tax escalator, by far the most effective energy-saving measure introduced by a British government, back in 1993 by Norman Lamont.

On education, Mr Brown’s main proposal is to spend more money on school buildings, but without any mention of what will be taught in these buildings or how. His second big idea was to commission a report on training, from Lord Leitch, a former insurance executive. Among the main outcomes of this report, whose publication was carefully timed to coincide with the PBR, will be the appointment of Sir Digby Jones as Mr Brown’s new Skills Envoy and the replacement of a tired old quango, the Sector Skills Development Agency, with a dynamic new public-private partnership called the Commission for Employment and Skills. When Mr Brown becomes Prime Minister we can presumably expect many more radical ideas of this kind.

Is it really possible that the most anticipated event in British political history — the Blair-Brown transition — will do nothing more in the end than create business opportunities for corporate logo designers and head-hunters who place retired businessmen and civil servants on government-sponsored boards?

It may seem unfair to judge Mr Brown so harshly on the basis of one lacklustre performance. But then, fairness rarely plays much part in politics. and yesterday’s PreBudget Report, like his equally disappointing speech to the Labour Party Conference in September, was supposed to be one of the critical occasions in his political life.

It is almost as if Mr Brown, having finally won his decade-long battle with Tony Blair to become Prime Minister, has begun to lose interest in this ultimate prize. If Mr Brown continues in this style much longer, our Rip Van Winkle can go back to sleep and wake up on the day after the next general election.

By then, he will have missed the whole of the brief Prime Ministerial career of Gordon Brown.

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