Not many parties are truly unforgettable; one of the few I can still recall is that held on 9 April 1992 at the Savoy Hotel by Conrad Black, at the time the proprietor of the Daily Telegraph. This was the night of the general election; and in the weeks leading up to it, as it seemed ever more likely that the Conservatives would lose power and Neil Kinnock would become Prime Minister, an increasing number of acceptances flowed in from Labour-supporting glitterati, anticipating the pleasure of seeing the humiliation not just of the Tories, but that of the host in particular, who would have to see them toasting the defeat of the party his newspapers supported with champagne he had paid for.

This point was made to me with undisguised delight at the beginning of the evening in question by Neil Kinnock's friend, the writer John Mortimer (who in any case never needed an excuse to drink good champagne). John was a man of outwardly sunny disposition; but I recall how his features hardened to a carapace of venomous rage as it became clear, from the first results, that the Tories were on course to win a fourth successive election.

The despondency that then enveloped Labour's supporters in the media – let alone the party itself – is hard now to imagine: Robert Harris accused the public as a whole of being "liars" and declared in his Sunday Times column that "the Labour Party, as presently constituted, will never again win an election".

Well, we all now know what happened next. Within months of the Conservatives' improbable victory in the midst of a recession, the pound sterling had been vomited out by the European Union's Exchange Rate Mechanism (ERM); and since our membership of this club had been hailed by Mr Major as the sole guarantor of our economic health and future prosperity, his party's reputation for competence was shredded beyond repair.

The political execution by the electorate was deferred for five years; but long before the Tories were obliterated in the 1997 general election, the more astute among its supporters had come to the conclusion that the party's biggest misfortune had been to win the previous one. This was in part because even from July 1992 Labour's then shadow chancellor, one Gordon Brown, had been as fanatically committed to the bitter end to our membership of the ERM as had Mr Major. Had Labour won the 1992 election, the economic circumstances which trashed both the currency and the occupants of Downing Street would have had exactly the same effect on a Kinnock administration.

In some ways, it might even have been worse for a Labour Government: since the party's reputation for economic competence was shaky in the first place, it would have dramatically reinforced the innate scepticism of the public about Labour's basic reliability.

So as David Cameron's Tories begin to show signs of panic at their recent falls in the opinion polls – one published this weekend had its lead over Labour cut to six points – I offer these memories to them by way of consolation and comfort. Of course, the Tory leadership desperately wants to win the general election this May (and are still favourites to do so); but they should also recognise that, in narrowly political terms, victory would do the Labour party no favours.

When James Purnell, one of the brightest of the Blairites, declared last week that he would not fight his seat at the general election, I wondered if his inner argument was not along these lines: that although it would be unpleasant to lose the election, he could still less bear to contemplate the thought of being a Labour Member of Parliament with Gordon Brown remaining Prime Minister, and party leader, after 6 May.

Leave aside the prospect of more years under the command of such a morbid misanthrope as Mr Brown (and it is this, rather than the Prime Minister's alleged bullying, which fills his colleagues with such despair); what is the political and economic inheritance which the Labour government would bequeath to its reconstituted self? The scene would be something like the end of Conrad's Heart of Darkness, when Kurtz in a sudden moment of realisation declares: "The Horror! The Horror!"

The victim of the former rugby-playing Prime Minister's hospital pass – as he has both shattered the country's finances while also making further commitments which can not possibly be afforded– would not be David Cameron, but himself. It would be Gordon Brown, Mr Public Investment, who would have to cut state expenditure on a scale which has never before been done in this country – a guarantee of vicious internecine conflict between the Labour Party and its main financial backers, the public-sector trade unions; either that or face such a buyers' strike on the part of international investors in Britain's vast debt as would require the final humiliation of a second Labour Government having to throw itself on the not so tender mercies of the International Monetary Fund.

David Cameron has no particular bragging rights in this matter; he it was who, before the credit crunch, had committed the Conservative Party to continue Labour's bizarrely counter-cyclical public expenditure policies, which have left the country with a colossal structural deficit quite distinct from the temporary problems of a recession. So when George Osborne routinely accuses Mr Brown of having "not fixed the roof while the sun was shining", we should recall that the Conservative Party's policy was precisely a commitment not to fix the same roof while that same sun was shining.

Still, as the events following the summer of 1992 demonstrate, there is little justice in politics; just as the then opposition politician Mr Brown was able to benefit from the collapse of a government economic policy which he had uncritically supported, so Mr Cameron has reason to hope to profit from the disintegration of a strategy to which he offered no criticism at the time.

Most likely, enough voters will be so desperate to see the back of Gordon Brown – the width and depth of the popular dislike of the Prime Minister inspires pollsters with awe – that David Cameron and George Osborne will get their chance to try to sort out the mess; yet there would also be a kind of macabre justice in the prospect of seeing a re-elected Labour Government split asunder against the fiscal rocks on to which it has steered the ship of state.

This is not completely improbable, given the peculiar bias of the electoral system, at least as it has operated against the Tories in recent elections. Remember also that, even if the Tories were to be the biggest party in a hung parliament after 6 May, that would not give Cameron the immediate right to try to form a government. The incumbent Prime Minister is constitutionally entitled to make such an attempt himself: that was what Ted Heath did in February 1974, with his admittedly futile effort to persuade the Liberal leader, Jeremy Thorpe, to support a Conservative Party which had fewer Parliamentary seats than Labour.