In the 1929 general election, Labour won 37% of the vote and became the biggest party in the House of Commons, but without an overall majority. Ramsay MacDonald cobbled together a minority government with Liberal support, including the first female cabinet minister, but he then struggled to control his troops after seeking to cut government spending when caught in a global economic maelstrom after the Wall Street crash.

Cabinet divisions grew as the economy weakened, unemployment soared and the government grappled with a £120m deficit. Having pledged to balance the books, MacDonald resigned in August 1931 and – encouraged by the palace – formed a national government to tackle the crisis, with the Conservatives joining his coalition. Two months later, this coalition won a landslide election victory.

The creation of a national government split two parties, destroyed MacDonald’s reputation on the left and, thanks to its later policy of appeasement, is often viewed as a disastrous experiment. But 84 years later, as this year’s general election campaign effectively begins, could we be on the point of seeing our latest economic and political crisis causing a repeat of history with another national government?

The two main parties are on the slide, their historic decline speeded up by an economic meltdown that fuelled discontent with their style of traditional politics and fostered the rise of insurgent parties. Labour remains marginally ahead but is distrusted on economic matters and held back by a leader who commands little confidence. The Tories have the most trusted leader, even on the sacred health service, yet voters think they care only for the rich, and remain wary of their stewardship of public services.

Both parties responded badly to the disruptive political climate, their fumbling reaction to Ukip’s rise in England and the SNP surge in Scotland boosting the insurgents while corroding their own brands. These are volatile times and anything could happen before voters go to the polls on 7 May, especially given a Greek election with potential to spark a eurozone crisis. But most people in Westminster privately predict a hung parliament.

Party leaders, however, may have to build broader coalitions than our current two-party version. I have heard one Downing Street insider punt the concept of a Tory-Lib Dem-Green coalition, a senior Tory suggest a Conservative-SNP deal based on faster devolution, and a Labour figure float a Labour-Lib Dem-SNP-Plaid Cymru agreement reliant on big tax rises and slower spending cuts. Any of these fragile groupings could be held hostage by single-minded militants or single-issue obsessives capable of collapsing the government.

Labour believes a strategy of clinging on to core voters can lead to triumph. Tory tacticians think they will be saved by the weakness of Ed Miliband. They argue that they can emerge as the biggest overall party and rule as a minority government until a second election later in the year, when enough voters, frustrated by instability, will return to the fold for an overall majority. Both approaches are profoundly pessimistic and undeserving of victory; they may also turn out to be pipe dreams, compounded by the potential of post-election challenges to party leaders.

The possibility of a full-blown constitutional crisis looms large. Curiously, this could be what the country needs to reboot its anachronistic political system. Yet it would come at a time of great global uncertainty; it might also plunge an elderly monarch into menacing political waters. Instead, as Labour and Tory leaders explore the post-electoral landscape, they may find coalition deals with insurgent forces too costly, minority government too impractical and a far better solution staring them in the face.

A government of national unity between Labour and the Conservatives may sound far-fetched, especially amid the froth and fury of a nascent election campaign. It would certainly be tricky, exacerbating internal divisions and leading to more defections. Yet, while there are serious disagreements, the two parties have more in common with each other than with the insurgents on many key issues – especially if David Cameron survived and Miliband was replaced by someone such as Chuka Umunna.

Elections are a form of crowdsourcing, the wisdom of crowds ensuring the result reflects national desire. Britain did not trust Neil Kinnock in 1992, then was desperate to kick out the Tories five years later. By 2010, the nation wanted Gordon Brown out and Cameron in, but was wary of claims of Tory modernisation – rightly, as it turned out. Yet now, a sceptical electorate does not want to hand either party untrammelled control of the country.

In keeping with the current mood, a national government would see Cameron remain prime minister and the Tories retain control of the Treasury (replicating how Labour held both posts in 1931). Labour’s leader would be deputy prime minister, with the party overseeing education and health, although presumably it would need to revert to its previous stance on private sector involvement.

Regardless of the personalities and positions, however, the two parties could start to hammer out those huge issues confronting the nation that conventional politics seems incapable of solving. These include the creation of a modern political system, the resolution of Britain’s haphazard drift into federalism and a workable funding solution to save the creaking NHS.

Four months ago, the mainstream party leaders put aside their differences and joined together to save the nation when it seemed Scotland would demand independence. It was a brief flicker of unity before they started to play the trivial pursuit of party politics again. Now it is possible to envisage that they might have to do the same again this year to save the nation from another constitutional crisis. It might even be for the best.