Not long after Gordon Brown takes his long-awaited drive from Downing Street to Buckingham Palace this year to kiss the hand of the Queen, a group of senior ministers will be waiting anxiously by the phone. For most of their fellows in the Government, this nervous moment will be about the anticipation of a big promotion, or dismissal, from the new Prime Minister. But for this select cadre, their prayer will instead be that the phone never rings.

These are the men (and one woman) in the running to take over from Mr Brown and become his Chancellor. Yet as they listen to the Treasury’s incumbent deliver his eleventh and last Budget this week, each of them will likely be murmuring a quiet prayer that they are not asked to fill his shoes. The chancellorship may be one of the three great offices of state, but holding the post in the impending Brown administration may be the ultimate poisoned chalice – a job from hell.

At one level the special poison in the Chancellor’s chalice is all about Mr Brown’s personality. After a decade at the Treasury, he knows it inside out and he is not about to relinquish control of Whitehall’s most powerful ministry simply because he has moved to No 10. Instead, as First Lord of the Treasury, he will intend to be just that. Indeed, Mr Brown plans to bale out of the Treasury having left it more or less on autopilot, having locked up all its main levers in the Budget this week and the autumn’s Comprehensive Spending Review.

With this policy autopilot preprogrammed, the relentless, restless new premier peering over his shoulder and Mr Brown’s chief lieutenant, Ed Balls, waiting in the wings to take over when the time is ripe, the new Chancellor will have scant discretion. Mr Brown may even lop off large parts of the Treasury and put them into a new ministry, radically curtailing the scope of the chancellorship through which he has exercised pretty much untrammelled power.

For the new Treasury chief, this lack of personal elbow room will be all the more painful because that person will also be strapped into corset-tight financial constraints that are set to prove highly politically stressful. The grim reality of Mr Brown’s bequest to his successor is one of unpaid bills, a vast overdraft and financial means that have been stretched to breaking point. The present Chancellor has taken Labour’s great tax-and-spend experiment more or less to its limits.

Since 2000 British public spending has been pushed up faster than in any other developed economy – more than three times as fast, in fact, as in the US, which has experienced the next most rapid pace of increase. Spending has risen by an annual average of 4 per cent in real, after-inflation terms. To pay for this the tax burden has also risen more sharply than in our leading competitor countries, to an extent that has strained public tolerance, provoked wails of fury from business and led the International Monetary Fund to give warning this month that further rises would be economically damaging.

Yet, despite billions in extra taxes, the public finances are badly stretched. Revenue shortfalls mean that Mr Brown has been forced to borrow a cumulative £170 billion since 2001 – about £100 billion more than he then intended, taking him to the brink of breaching his self-imposed fiscal rules.

The consequences that confront the Chancellor’s successor will be confirmed by Mr Brown this week. Public spending plans are to swing back from feast to relative famine. Spending growth will be screwed down to as little as 1.9 per cent a year in real terms from 2008 onwards, perhaps less. Some departments will face real-terms cuts while also being pressed to eliminate public sector jobs and deliver efficiency savings of 3 per cent a year.

It remains to be seen whether Mr Brown and his successor can make this “eye-wateringly tight” spending squeeze stick. But there are compelling political and economic reasons to do so. Politically, the new premier will want to build up a war chest for the next election. A bout of greater fiscal austerity is also essential if the Treasury is not to break the financial strictures imposed by Mr Brown – something he will hardly want to see from No 10. Most crucially, a financial cushion needs to be built up against the threat of a new economic downturn, the odds of which can only rise as Britain continues the protracted run of unchecked growth of which the Chancellor likes to boast.

None of this will be easy for the next Chancellor to secure. Nor will it be a recipe for popularity, with the public or the party. Scarce resources will throw into question the Government’s ability to deliver Labour’s social priorities, such as cutting child and pensioner poverty. Neither that nor taking the axe to more public sector jobs while screwing down hard on wages will be popular with Labour activists and the unions. And even with the lion’s share of the cash that is available going to still-hefty increases in health and schools spending, should persistent public dissatisfaction with key services fail to abate, the pressures to loosen the budget screws could quickly mount.

This unappealing job offer will be still more unappetising to the candidates when they consider that not only has Mr Brown largely emptied the Treasury’s box of financial tricks to keep his own show on the road for the past ten years, but that the awkward scenario above is based on everything going mainly right. And there is plenty that can go badly wrong.

If the economy were to hit rockier times, thanks to, say, a new oil shock, a Middle Eastern war or a US slump, it would not have the extra fuel from strong public spending growth that staved off threatened recession at the start of the decade. And with the fiscal rules already at breaking point, statistical accounting changes forcing the Treasury to put more of its concealed public debt on the books could make life harder still.

Applications in writing, then, for the worst job in Britain to G. Brown, Downing Street, London.

— The probable plight of the next Chancellor ought to be a joy for George Osborne, his Conservative Shadow. Yet any Osborne Schadenfreude may be lessened by the knowledge that his own policies are so little different from Mr Brown’s that, were he to inherit the Treasury after the next election, he could face an equally miserable time.

Still, I hear that Mr Osborne is mulling at least one radical policy. I gather that he has become keen on a switch from taxing income to more taxes on consumption – that is, spending. Economists see consumption taxes as less distorting to economic activity, while they can also be used to shape greener behaviour, part of their appeal to the Tories.

The trouble for Mr Osborne will be that not only are taxes on spending regressive – hitting the poorest harder – they are also a hard sell. Shadow Cabinet members already have been told to brace themselves for new, unpopular policy proposals.

But this idea may yet end up in the long grass – alongside Mr Osborne’s once-favoured flat-tax wheeze, ditched after he realised how hard that would hit Middle Britain.

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