“All countries have their difficult eras – periods of national embarrassment,” observed Andy Beckett in his 2009 book on Britain in the Seventies, “of slipping confidence, of decline, of crisis, both real and imagined.”

In a few weeks’ time, I’ll turn 40, which has got me thinking about parallels between the decade of my birth – the 1970s – and the similarly volatile 2010s.

Back in August 1977, the Scotland and Wales Bill had been guillotined, apparently risking the devolution project, while the minority government of James Callaghan had recently agreed a stabilising “pact” with the Liberals.

The economy, meanwhile, was in flux, as were the fortunes of the Scottish National Party, which appeared to be on the wane following electoral breakthrough in the two general elections of 1974.

Throw in a referendum on Europe in 1975 and “direct rule” for Northern Ireland at the beginning of the decade, and you’ll see what I’m driving at. One can overdo the echoes (and I probably am), but the most compelling is the feeling of a major shift in long-standing political orthodoxy.

In the 1970s it was the decline of what historians call the “post-war consensus”, a shared left/right pursuit of full employment, a mixed economy and cradle-to-grave benefits. By the time I was born, political parties were responding to this in different ways: Conservatives by pitching rightward, Labour towards the centre and the SNP via independence.

A similar feeling permeates today’s political atmosphere, only this time it’s another cross-party orthodoxy that’s breaking down, what might be called the Thatcher/Blair “neoliberal” consensus, ie a shared belief in low taxation, fiscal prudence and as liberal a regulatory regime as it’s possible to sustain.

The party-political response, however, has flipped. “We used to think you could spend your way out of recession and increase employment by boosting government spending,” was James Callaghan’s famous line at the 1976 Labour Party conference. “I tell you, in all candour, that that option no longer exists.”

One suspects Jeremy Corbyn, very much a politician of the 1970s, heard those words and marked Sunny Jim down as a Tory sell out. As foreign secretary, Callaghan had also “renegotiated” the UK’s terms of Common Market membership and supported a “Yes” vote in the 1975 referendum.

So, today’s Labour Party, once again split over Europe, is tacking left rather than right, while the Conservatives move in the opposite direction. Generally overlooked in the recent election was the Tory manifesto’s Callaghan-like mea culpa, an acknowledgement that tax rises and state intervention might be necessary to combat inter-generational inequality.

And with the Tory-DUP agreement making the Lib-Lab Pact look like a walk in the park (Arlene Foster proved a better negotiator than David Steel), the Conservatives will be compelled to further triangulate, not just on abortion for women in Northern Ireland, but on public-sector pay, school spending and even tuition fees. Austerity appears to have had its day. I recently asked a Tory contact what the UK Government’s economic policy was. “We don’t have one,” he replied matter-of-factly.

This points to another contrast between now and the 1970s, and a damaging one at that. Sure, the politicians who dominated four decades ago were often divisive figures, but few doubted their intellectual capacity. Callaghan and Thatcher, Healey and Howe, or Crosland and Pym all had a grasp of political economy and foreign affairs that at least produced a coherent policy response.

At present, all we have are Theresa May and Jezza, both of whom talk about a “new economic model” without having the slightest clue what that means. Foreign policy, much neglected over the past decade, is now seen as an irrelevance, while there’s an ongoing temptation to retreat into quick fixes: leave the European Union! Nationalise the railways!

The newer generation of leaders, meanwhile, has a deeper problem. Sturgeon, Davidson, Dugdale et al all came of political age in the 1990s or after, and therefore missed the big ideological battles of old. And with Western liberal democracy apparently triumphant, they cut their teeth as campaigners and media performers rather than deep thinkers, the result of which is a shallow political arena preoccupied with headlines and tactics.

In an elegant essay in yesterday’s Sunday Herald, Neal Ascherson reckoned the “idea” of independence might have entered Scotland’s “bloodstream” in the 1970s, just “as the SNP began to score victories”. But as anyone familiar with Nationalist history will know, the story of the SNP is one of electoral peaks and troughs, political breakthroughs followed by listless decline.

Again, history repeats. In October 1974, the SNP’s 11 MPs and 30 per cent of the vote was regarded as a political earthquake, a result with interesting echoes in the Scottish Conservative showing just a few weeks ago. But by 1978 the party appeared to have run out of steam, losing a string of once-winnable by-elections, and split in Parliament between left-wing radicals and rural conservatives.

In other words, after a few years in which voters and journalists suspended their disbelief in the face of political novelty, Scottish Nationalism began to sag under the weight of its own significant contradictions. Sure, the trough won’t be as deep this time round – in 1979 the SNP only managed just 2 MPs and 17 per cent of the vote – but it’ll be some time before it can dig itself out.

Political predictions are now a mug’s game but my sense is that the events in Scottish and UK politics since 2007 still have some time to play out, for the new landscape to reveal itself. At present, there’s lots of grasping for future points of certainty, ie the “end” of Brexit negotiations in 2019 or the next Holyrood elections in 2021, but that seems quixotic.

Politics in the 1970s, to quote Andy Beckett again, “was about moments of possibility as well as periods of entropy; about stretches of calm as well as sudden calamity.”

But no one, not Mrs May, Mr Corbyn and in Scotland Ms Sturgeon and Ms Davidson, have even come close to grappling with the challenges we face beyond their usual soundbites; none has identified any remotely credible possibilities. Perhaps in 2027 when, God willing, I’ll be approaching my half century, things will be clearer.