It’s official. The north-south divide in Britain is now wider than at any time since the beginning of the industrial revolution – wider than when Charles Dickens was writing about Victorian squalor, and wider than in the depression years of the 1930s, when George Orwell exposed the grinding poverty of northern England in The Road to Wigan Pier.

Remarkable new evidence from a study by the academic Philip McCann, The UK Regional-National Economic Problem, shows that while economic output per head, measured by gross value added, is near £43,000 a year in London – and as high as £135,000 in inner west London – almost half the UK population lives, in regions where output per head is below £22,325.

Indeed the regional divide is so vast that, at £13,500 per person, economic output in Gwent, Wales, is a tenth that of one of the wealthiest part of London; and in the Tees and Welsh valleys it has now fallen below that of Lithuania, Slovenia and Slovakia.

Of course, in both the north and south we are all better off than 100 years ago, but the divide in income, jobs and pay is increasing faster than ever. Average household incomes in Wales, Northern Ireland and the northern regions of England are around 60% of those in Greater London. Last year, when jobs rose by 277,000 in London they rose by only 1,000 in the north-west and fell by 40,000 in the north-east. In London 10% of workers are officially low paid. In the north the figure is 25%.

Nothing the chancellor’s autumn statement can offer will be sufficient to bridge this divide

It was a revolt of the regions – northern industrial towns hit by wave after wave of crushing global change – that pushed the Brexit vote over the edge. Sadly, with the north more dependent on European trade – 59% of the north-east’s goods exports go to the European Union against only 39% of London’s – the post-referendum optimism felt by northern leave voters will be short lived, as standards of living fall faster and even more jobs are lost in leave-voting areas.

Nothing the chancellor’s autumn statement can offer will be sufficient to bridge this divide. Historical gaps in infrastructure spending are set only to widen over the next few years: transport investment per head will be £1,900 a year in London between now and 2020 but less than £300 in the north-east. Three-quarters of Government and Research Council research and development spending is in the southern third of the country while the north-east receives only 7%. Even talk of a “northern powerhouse” cannot obscure a cut in regional aid from £3.3bn a year in the first decade of the century to around £2bn in the second.

All this leaves us with a United Kingdom that is united in name only. Britain now has the most extreme inter-regional inequalities of any country in western Europe, yet the biggest concentration of political power in a centre that is singularly ill equipped to narrow the divide. Quite simply, our London-centric constitution has failed to unlock the potential, unleash the enterprise, or even meet the needs and aspirations of, our northern regions.

And this centralisation does not even meet the needs of London. While northern communities live with long-term unemployment, forced migration and in some cases depopulation, the capital city struggles with congestion, overheating, high house prices and poor housing supply – challenges that a more balanced regional policy could address.

London’s financial district. Photograph: Hannah Mckay/Reuters

So we need to engage the regions and nations in a UK–wide debate that is about much more than the terms of Brexit. For this reason, I advocate a People’s Constitutional Convention, modelled on the successful Scottish convention of 1989, which energised Scotland and built a consensus for progressive change. Such a gathering should start with everyday concerns – how to create more jobs, raise living standards and improve services – and ask what constitutional settlement can best meet our needs and aspirations.

A people’s convention could propose more power for the north and, in turn, encourage an outpouring of innovation, creativity and local decision-making in each region and nation. Such a convention could explore a more federal way for resolving the future role of Scotland, Wales and Northern Ireland in the UK.

After last week’s Brexit court judgment, the regions and nations could unite and demand a better deal under article 50. Powers now held in Brussels – from decisions concerning regional policy, agriculture and fisheries, to social and environmental protection – should be repatriated not to Whitehall but to the regions and nations, giving them power over £2bn-£3bn of public spending.

There is no going back to pre-23 June Britain. What is open to us is a fresh and more expansive vision of Britain than the Tory Brexiteers could ever deliver, in which we view Britain not through the lens of London but as an association of four nations and many distinct regions, whose potential remains largely untapped, and which are at their best when local initiative is unlocked and the right balance is struck between the autonomy our communities desire and the co-operation we need.

A new and different Britain – empowered, confident and outward-looking – is the answer to the harsher, shriller version of Brexit Britain on display at the Conservative conference. A party that questions the right of EU nationals to stay in Britain, then proposes employers single out the foreigners in their workforces, and ridicules any notion that we could think of ourselves as citizens of both Britain and the world, is not going to build the Britain our young people want.

The Labour party should now ask the government to sponsor a convention. If ministers refuse – as happened in Scotland in 1989 – then Labour should invite the other political parties to join them. The convention should engage citizens outside the established political process and should rule out nothing – from a written constitution on federal lines to an elected Senate of the Nations and Regions to replace the unelected House of Lords. Out of such a gathering can emerge a more tolerant, inclusive, equal and outward-looking Britain – the best alternative to the Conservatives’ hard-Brexit Britain. For an even bigger decision than what type of Brexit we want to end up with is what kind of nation we seek to become.