Spare a moment for the union, buried by its own defenders. The Conservatives have opted to fan English nationalism and resentment, both to peel off voters in key English marginals and to delegitimise any future Labour government backed by the SNP. Such nationalist resentment cannot be stoked and then neatly placed back into a box when it has outlived its use, discarded until deemed useful when another political crisis arises. English nationalism is set to become a mighty force over the next five years, whoever governs, and it may well help to consume an already disintegrating union.

The union was always a curious construction, as any supporter of Scottish independence will tell you: imposed by elites, and then cemented after the event. It was bound by empire, in which Scottish and English rulers shared the spoils; by a labour movement that united workers on both sides of the border and built a common sense of solidarity; by the welfare state, with its national, redistributive institutions. But the empire, thankfully, is gone. Less welcome has been the erosion of the welfare state and the labour movement. Scottish Toryism met its nemesis in the decline of religious sectarianism and the rise of Thatcherism, while Labour surrendered acres of progressive political space, its MPs often presiding over rotten boroughs.

When Labour disastrously formed an alliance with the Tories in a campaign of fear in the runup to the referendum – and I take no pleasure in being among the voices at the time who warned of the consequences – a once mighty Scottish Labourism was revealed to rest on sand, and has all but imploded. The union’s bonds are now weak indeed.

When the campaign of fear during the referendum appeared to be failing or even backfiring, the Tories resorted to begging Scotland to remain. Within hours of the result becoming clear, the Tories swiftly shifted to tapping into English grievance with “English votes for English laws”, seeking to establish a two-tier parliament. Throughout this election campaign, the rightwing media – acting as propaganda outlets of the Tory party in some cases – have engaged in an ever more hysterical campaign over the SNP. The Sun dressed up Nicola Sturgeon as Miley Cyrus, riding a wrecking ball engraved with “Tartan Barmy”, a toxic blend of sexism and xenophobia. The Tories portray the likely democratically elected representatives of Scotland as akin to agents of a foreign power, illegitimately having a say in the Westminster parliament to which they have been sent by their British constituents.

Owen Jones urges viewers to use their vote Guardian

Whatever happens now, English nationalism will be potent indeed. If the Tories triumph, possibly backed up by the DUP and Ukip, the government will almost certainly contain not a single Scottish MP. It will be an English nationalist government, pledged to resist the demands of Scotland in the thrall of the SNP. If a left-of-centre majority is returned on Thursday, David Cameron will likely lock himself in No 10 for as long as possible, relying on an even more hysterical anti-SNP media campaign to delegitimise a Labour-led government. In opposition, an ever more Ukipised Tory party will undoubtedly adopt an ever clearer English nationalist bent. Scots have already been maliciously portrayed as subsidy junkies by rightwing political elements and much of the media. A narrative beckons of England at the mercy of feckless, duplicitous Scots.

As a plastic northerner, I feel London is a world removed from the Stockport of my childhood

What is the way out? Are we condemned to be a disintegrating country awash with resentment and jingoism? Englishness is inherently vague, and has been left to be defined by elites and reactionary forces. In practice, the Englishnesses of a Cornish farmer, a London supermarket worker, a Manchester business owner and a Northumberland ex-miner are rather different. As a plastic northerner, I have lived in London for many years, and it feels a world removed from the Stockport of my childhood.

Personally, I always feel at my most English when I’m abroad and struggling to locate a decent cup of tea. English identity is certainly much stronger now than it was, but it seems too often to be defined negatively: as not Scottish, as hostile to immigrants and Muslims and the “other” generally. The Englishness of popular struggle against authority – the civil war, the levellers, the chartists, the suffragettes, the labour movement – is intentionally airbrushed out of existence. This history and identity – inclusive, linked to struggles for justice in other countries – surely needs to be reclaimed. An Englishness based on chauvinism and resentment needs to be urgently displaced.

The old constitutional order must fall, too. Yet another hung parliament must rightly mean renewed calls to replace an electoral system that no longer produces decisive results. But to defeat a political right intent on fuelling rampant English nationalism, we must go further. A federal Britain must surely be built, balancing devolution with greater redistribution of wealth and power. The political agenda must include regional assemblies, alongside genuine powers for local authorities. A new populism should unite English, Welsh and Scots alike against a self-interested rapacious elite; a thriving City of London as much to the hundreds of thousands of the capital’s children who grow up amid financial hardship in overcrowded homes as it does to the young in Wales, Scotland or northern England. Workers condemned to poverty wages, job insecurity and a growing housing crisis must be united against a common enemy: an elite that all too often doesn’t pay either proper taxes or proper wages.

A new populism should unite English, Welsh and Scots alike against a self-interested rapacious elite

The Tory and media campaign of fanning resentful nationalism has been clever, co-ordinated, and probably quite successful. Tragically, it may well be a portent of what is to come. This English jingoism is most lethal to the English themselves, defining their enemies not as the great injustices that scar English society, but Scots and immigrants. There has been little effective response to it so far. If this country has a future, then it must come soon.

• Jonathan Freedland is hosting Guardian Live: Election results special, on Friday 8 May at 6pm in Kings Place, London. Polly Toynbee is a panellist. For full details and to book tickets, see here