The general election in May is compelling in its unpredictability. Unusually for a British election, no one has a clue which party or parties will form the next government. But the dark, foggy political landscape is not entirely unfamiliar. We have been here before. There are many parallels with the election of February 1974 and the one that followed in October the same year. What happened then is illuminating for what might or should happen once the votes are cast on 7 May.

In February 1974 the outcome of the election was ridiculously close. The Conservative party won a few more votes than Labour, but Labour won four more seats. The incumbent Tory prime minister, Edward Heath, sought to form a coalition with the Liberal leader Jeremy Thorpe. Initially Thorpe was quite keen, but his senior parliamentary colleagues expressed alarm. A significant number of Conservative MPs were strongly opposed too.

Heath resigned and the Labour leader Harold Wilson became PM, at the head of a minority government. Wilson had temporarily united his divided party by offering an in-out referendum on EU membership, and had fought the election partly by highlighting the cost-of-living crisis. The minority government lasted for a few months until Wilson called a second election in October 1974, a contest he won with a small overall majority.

The similarities extend well beyond the closeness of the race. Both main party leaders were troubled by internal critics, as they have been in this parliament. From the right Norman Tebbit, then a backbench MP, despaired of what he took to be Heath’s weak-kneed pragmatism. On the Labour side, several of Wilson’s senior colleagues confided in their diaries that they expected to lose the February election and that the campaign would mark Wilson’s final days as leader. Senior figures in both parties had doubts about the qualities of their leaders. The same applies now.

As the Tories and Labour struggled to prevail, other parties unexpectedly soared. The Liberals secured 6m votes, a huge leap. The SNP doubled its share of the vote in Scotland. Breathing down Labour’s neck, the nationalists were big players in the new hung parliament. Labour was both threatened by the SNP and yet dependent on it to survive as a minority government.

Leaders in 1974 turned back to familiar ideas even if, in doing so, they voluntarily walked towards their own doom

There is a deeper parallel between February 1974 and now. Both the bigger parties struggled to make sense of the daunting economic challenges, as unions flexed their muscles and the price of oil quadrupled. The leaderships clung to old orthodoxies, failing to find fresh ideas that both commanded wide electoral appeal and addressed the demands of dramatically changing times. Today the leaderships of both the bigger parties dance to similar tunes in relation to the deficit, although both tentatively grappled with new approaches, David Cameron with his “big society” and Ed Miliband with his advocacy of active government. Leaders in 1974 turned back to familiar ideas even if, in doing so, they voluntarily walked towards their own doom. The same might happen in May 2015.

I have interviewed some of the key players from that period for a BBC radio programme on 1974. Their direct experiences provide a route map for the coming turbulent months.

Shirley Williams was a cabinet minister in the minority government. Along with all the obvious fragilities of such an arrangement she adds another: she says being a cabinet minister in a minority government is so physically exhausting that it cannot survive for very long. She was one of the younger members of the cabinet and yet recalls the impossible demands of running a department, fulfilling party responsibilities and attending knife-edge votes in the Commons late at night. She finds it hard to envisage a coalition forming this May, and yet knows that a minority government cannot last without its senior members collapsing from exhaustion.

All those I spoke to noted how brilliantly wily Wilson was as PM, outmanoeuvring internal and external opponents every frantic hour of the never-ending days. Neither Cameron nor Miliband are known for their strategic wiliness and are not in Wilson’s league. They would not survive long as leaders of a minority government.

So one lesson from 1974 is that for the leaders of the larger parties, a coalition is worth striving for. I did not expect to write that sentence. I can only see insurmountable obstacles to any possible coalition being formed in May. But the alternative is not sustainable either.

The surprise star of the October election for the Conservatives was Margaret Thatcher. The next year she was leader

Perhaps there will be a second election soon after May. But that was problematic in 1974. The parties had more or less run out of cash and campaigning energy. David Steel, then a Liberal MP, recalls that his party came up with the slogan “One more heave”. Exhausted strategists did not spot that the words could be misinterpreted as an instruction to vomit.

There are two other big lessons from that distant era. Although Wilson’s offer of a referendum on Europe helped him get through two elections in 1974, the actual plebiscite the following year settled very little in his party. By 1980 Labour was pledged to leave Europe, and former cabinet ministers set up the SDP partly in response.

After the coming election either the Tories or Labour will almost certainly hold a leadership contest. Perhaps the Liberal Democrats will do so too.Election campaigns matter in determining who will seize the crown. The surprise star of the 1974 October election for the Tories was Margaret Thatcher, who as shadow environment secretary promised to reduce local taxes and to intervene, Miliband-style, to reduce interest rates. Early the following year she was the leader of her party.

Of course there are many contrasts between then and now. The economic challenges in 1974 were incomparably different. But the financial crash in 2008 marked the end of an era, just as the disruptive strikes signalled the breakdown of the old corporatist consensus back then.

While we navigate towards a new set of ideas, politics is in a similar state of flux. Both Thatcher and Tony Blair are still cited by some in the Conservative and Labour parties as models for their leaders. Cameron and Miliband would do better to learn the lessons of the draining political dramas of 1974.

• Steve Richards presents Archive on 4: Coups and Coalitions: The Two Elections of 1974 on BBC Radio 4 on 7 February at 8pm