Gordon Brown has become a global leader. Despite his social awkwardness and tendency to moodiness, he has forged relationships across the world with presidents and prime ministers. Their words of praise for him at the G20 summit surpassed what was required out of courtesy to the host. Clearly they thought his energy had achieved for them all a respectable outcome. The stock markets seemed to agree.

It must be indescribably satisfying for the prime minister. Like his predecessor he has won global recognition, but, unlike Tony Blair, Brown has achieved it without going to war. Indeed, under Brown, British forces have quietly slipped away from Iraq.

Like Blair, Brown uses his position on the world stage to shape his image as a leader at home. A few months back, as he fumbled domestic policy, he did indeed resemble Mr Bean (as in Vince Cable’s memorable description); that joke would not work now.

It is remarkable that Britain, for all its diminished role in international affairs, has produced Winston Churchill, Margaret Thatcher, Blair and Brown, all of whom in their own time might have been identified approvingly by members of the public around the world. But while Brown must find it thrilling to be on that list, it is not necessarily encouraging. Churchill was defeated in an electoral landslide after leading Britain to victory over Nazi Germany. Thatcher and Blair were ousted by their own parties even though each had delivered three terms in office.

Maybe there is a link between global plaudits and national downfall. Perhaps the heady pleasure of international recognition leads a leader to despise, or at least neglect, domestic concerns. How contemptible the little-minded careerists in the House of Commons must seem to one who has been lauded by the world’s top 20 leaders. Everyone remarks on Brown’s new self-confidence. Here is a man who now looks you in the eye and bounds up palatial staircases two steps at a time.

Is it the right kind of self-assurance? John Major was not a global figure but, in the 1992 election, he alone thought he could win and spent the campaign standing on a soapbox in market towns. That was a useful sort of self-belief because it took him closer to people’s concerns. You sense Brown must find it harder than before to focus on bankers’ pensions, hospitals and police performance when his brain teems with schemes for global finance.

Still, for his political opponents Brown’s new-found status and state of mind present problems. David Cameron must not waste energy thinking how little Brown deserves his reversal of fortune. Truly, on the whole face of the planet there is no politician still in office more culpable for our present economic woes than Brown. Second only to the departed George W Bush, he drove his domestic economy rashly, arrogantly believing he had abolished the economic cycle. He encouraged recklessness in the financial services industry and failed in his duty of supervision.

However, if Menachem Begin could go from leading Irgun, the Jewish terrorist group, to winning the Nobel peace prize, and if Martin McGuinness could move from being a Provisional IRA commander to assuming office as a minister in Northern Ireland, why should we be surprised if Brown is now hailed as an economic saviour rather than a wrecker? Never expect fairness in politics.

Brown’s changing luck has presented a challenge for the Conservatives. An opposition party needs a consistent line of attack but that has proved impossible as Brown has ricocheted from disaster to recovery. The prime minister’s ability to pick himself up off the floor is his most unexpected and unnerving trait.

In reality, Brown is sprinting for an exit across open ground and could come another cropper at any moment. With more than a year left until the latest possible election date, he could be felled by a collapse of sterling or a crisis in funding Britain’s huge national borrowings.

For the Tories it is not enough to rely on the misfortune of the government. Its luck may hold or perhaps it could turn another disaster to its advantage. So Cameron and George Osborne, the shadow chancellor, have ventured onto a high ledge of political risk by proposing an alternative economic strategy. Encouragingly, fortune has favoured their bravery thus far.

When they first dissented from Brown’s policy of increasing spending and borrowing, they were isolated. Now large parts of the British media see things their way and their thinking is in line with most governments in the European Union. The governor of the Bank of England has forced Brown to abandon further fiscal stimulus.

Cameron and Osborne don’t exactly look comfortable on the lofty perch of fiscal responsibility. It may be safe to suggest that the partly nationalised banks will be cut down in size, but that saves not a penny of state expenditure. It is electorally dangerous to talk of reneging on public-sector pay deals or cutting back on the pensions of public servants. If the Tories do not intend to take those actions, though, where is the significant difference on economic policy between them and Labour?

As the Conservatives approached electoral disaster in 1997, I noticed that our erstwhile supporters were alienated less by our big failure – being forced out of the European exchange-rate mechanism – and more by a generalised feeling that life had become unfair. The government was somehow rewarding the undeserving while neglecting the self-reliant and law-abiding. I have the same feeling today. Unemployment and negative equity do the government no favours, but the malaise affecting Labour’s popularity is more complex. There is a broad perception that Britain is full of rogues who get away with it at the expense of the righteous.

Jacqui Smith, the home secretary, provides a splendid focus for resentment. If Labour loses, she has earned her own chapter in the history of that defeat. She has lost every shred of dignity with her expenses claims and compounds her error with media appearances in which she veers from stroppiness to contrition. Sacking her would help, although Brown is rightly worried that one minister after another will be sliced off by the media salami cutter.

Incompetence seems universal. Recently the police have apologised for the gross mishandling of two rape cases, an officer has been suspended over the death of Ian Tomlinson during the G20 protest and Bob Quick has resigned as head of counterterrorism after compromising a vital investigation.

Every day the public is given new reasons for rage. Sir Philip Hampton, the new chairman of Royal Bank of Scotland, described the business as “very successful” with “fundamental strengths”. Actually, it lost £24 billion in one year, dumped £325 billion of toxic assets on the taxpayer and ruined those who held its shares.

After Stafford hospital’s negligence led to the deaths of hundreds of patients, Cynthia Bower, whose organisation was supposed to monitor its standards, has been appointed chief of the Care Quality Commission, a promotion that one lobby group thought was an April fool. The authorities have decided not to investigate 10 other health authorities with worse morbidity records than Staffordshire. Could that be because it might expose incompetence among our well-paid regulators?

These examples destroy the public’s patience with government. Wherever the voter looks, there are snouts in the trough. It is that sense of injustice that poses the greatest threat to Brown. Maybe he cannot smell the danger as he circumnavigates the world.

Still, his global status challenges Cameron. Gordon has what it takes, but does David? It is the most tiresome sort of question. It is impossible to demonstrate that you can do the job before you actually get it.

Martin Ivens is away

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