Its work has barely started, but the government led by Boris Johnson has already transformed British politics. It was all clear by 5am on 13 December, in that great swath of once-safe Labour seats taken by the Conservatives, crudely understood as being leave-supporting, post-industrial and largely working class: Bolsover, Bishop Auckland, Bridgend, Great Grimsby, Durham North West, Wakefield, Wrexham, Bassetlaw.

In the three weeks since they turned blue, there has been a lot of talk about how places so ill-served by Tory governments could have elected Conservative MPs, but that misses a crucial point. Our convoluted electoral system has long ensured that the most reliable way a place can get political attention is by being part of a marginal constituency. And however it has happened, all those seats that were once solid parts of Labour’s “red wall” have now pulled this off, propelling themselves to the heart of the national conversation.

Given the Tories’ responsibility for the dire inequalities of the last 40 years, the natural reaction might be to scoff

In that sense, a new decade marks the start of a completely new political model. At its heart will be people such as the man I met on election night in Tunstall, one of the six towns that make up Stoke-on-Trent, where all three parliamentary seats are now held by the Tories. He answered the door to Labour canvassers and said he had just voted Conservative for the first time in his life. How did that feel? “Not good, really,” he told me. For the foreseeable future, politics will be full of the questions that lurked in that brief conversation. Can such voters be turned into enthusiastic Tories? Will Labour win them back? And in the course of the resulting battle, how will things change on the ground?

Over the Christmas break I dug out an old article from the Times, published towards the end of Tony Blair’s time in power. Its author had got hold of Labour research that emphasised how, back then, elections were still decided by much the same people who held sway in the 1980s: “young families with mortgages, working in the private sector in technical white collar or highly skilled manual work” and “self-employed workers with small businesses”, clustered in the south-east, the more affluent areas of the Midlands and towns and cities such as Bristol, Milton Keynes, Swindon and Gloucester.

We all know what the privileging of such voters meant in practice: they were understood by both main parties as wanting to hold the post-Thatcher settlement intact, and keep government intervention in the economy (and their taxes) to a minimum, and yet somehow still be confident of well-funded public services. During the David Cameron years the same voters were held to accept the wisdom of austerity but also to be socially liberal and support his attempts to modernise his party.

If Labour is ever to form a majority government, people and places like these will still be crucial. But the party is first going to have win back rather different voters in its lost heartlands. For the Tories, meanwhile, post-Brexit hegemony now depends on the support of traditionally Labour-supporting areas that have long relied on the welfare state and public sector, and have stuck with communitarian values that post-Thatcher Conservatives never seemed to understand.

Facebook Twitter Pinterest ‘The inescapable realities of a redrawn political map.’ Flags on display in a residential tower block, Stoke-on–Trent. Photograph: Oli Scarff/AFP/Getty Images

The mantra “Get Brexit done”, and hostile Tory noises about immigration and crime and punishment, are part of the drive to keep these places onside, but what they fundamentally require from politicians is much more onerous: since the 2016 referendum, large parts of the country have been demanding serious economic change, now long overdue.

Last week I had a long conversation with a senior minister. As surprising as it may sound, he insisted that some very prominent strands of Conservative thinking were now in retreat. Unprompted, he mentioned an infamous free-market tract co-written by some of the people he serves alongside. “Things like Britannia Unchained, and those past Conservative plans to remodel the NHS – that’s all off the agenda,” he said. He talked about “problems with the capitalism we’ve had over the last three decades”, and the sense that “some of the things we’ve celebrated have led us astray”.

There was mention of big employers who “don’t have a sense of being rooted in the community”, and one of the most overlooked challenges faced by countless places: how to develop parts of the country that have fallen behind, and how to encourage people who’ve left to find opportunity elsewhere to come home.

Given the Tories’ deep responsibility for the dire inequalities and imbalances that have befallen Britain over the last 40 years, the natural reaction may be to scoff. Seeking a crumb of comfort from last month’s drubbing, some on the left might claim that credit for these shifts lies with Jeremy Corbyn and John McDonnell. In fact, such ideas have been bubbling away in Conservative politics for the best part of a decade, as evidenced by sporadic talk about “blue-collar conservatism”, Theresa May’s fleeting embrace of the “just about managing”, and the kind of approaches long associated with the estranged Tory grandee Michael Heseltine. Johnson himself has reportedly told the cabinet that he now sees himself as “basically a Brexity Hezza”.

Obviously, plenty of things are likely to remain exactly as they are, from the cruelties of the benefits system to the decay of vitalcouncil services delivered by councils. Reliable estimates suggest that public spending outside the NHS will still be 14% lower by 2024 than it was in 2010. The encroaching realities of Brexit could fatally undermine the Tories’ appeal in large parts of the Midlands and the north, as investment slows and industries are upturned. Meanwhile, younger people’s antipathy to the party and the leftward drift of England’s cities and suburbs still highlight big questions about the Tories’ long-term future.

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But something is definitely happening. Johnson has already set great store by a 50p an hour rise in the minimum wage that will increase some people’s earnings by nearly £1,000 a year. The government is reportedly planning to spend around £100bn over the next five years on infrastructure projects. There is talk of rewriting Treasury spending rules to decisively tilt public investment away from London and the south-east, and the “northern powerhouse” is suddenly back in vogue. And, jangling the nerves of Tory free marketeers, Johnson now talks about Brexit giving Britain the chance to bin EU rules about state aid, thereby allowing government to help troubled companies.

A month on from the election, these things are less about ideological fashion than the inescapable realities of a redrawn political map. On election night, the prime minister marvelled at how the Tories could suddenly claim to speak “for everyone from Woking to Workington … [and] from Wimbledon to Wolverhampton”. To hold this delicate coalition together will require not just the kind of shifts more thoughtful Tories are now talking about, but further changes in thinking that will jar against some of the party’s deepest beliefs. Beyond Brexit, whether Johnson and his allies can achieve such feats will be one of the most compelling questions of the next five years.

• John Harris is a Guardian columnist