Place has always been destiny in Britain, but never more so than in 2018. Pity the child born in Weymouth, Corby or Carlisle, locked into poor schools, a lacklustre economy and few decent jobs; if he or she had been lucky enough to be born in Tower Hamlets, Hackney or Westminster, their life chances might have been transformed. Where you are born in Britain, and England in particular, is becoming ever more a treacherous geographical lottery.

Nor is the divide any more just the well-known one between north and south. So relatively strong are the performances of Bristol and Manchester, with Liverpool hard on their heels, that overlaid on the old north-south split is the beginnings of a new one – an east-west divide. Parts of the north-west such as Trafford and North Cheshire are strong economic and social performers, while the towns along the M4 and Bristol itself are doing pretty well.

Since the financial crisis, two western regions of England – the north-west and West Midlands – have been growing at twice the rate of the east. The Financial Times reported on 14 Februarythat the average output per head from the west’s workers is now a full £2,000 higher than for those in the East Midlands, Yorkshire and the north-east – and the gap is widening. Productivity is growing faster in the west as a result, and business confidence in the north-west is much higher than the national average.

The numbers don’t challenge the greater reality – that the difference between our leading city, London, and the rest is the biggest of any country in Europe. The two western regions of England may be doing better than the east, but their output per head is still only three-quarters of London’s. On top, London boasts nearly all the “social mobility hotspots”, as the Social Mobility Commission calls them. Two-thirds of children going to school in Westminster and receiving free school meals will get A* to C grades in maths and English at GCSE; in towns such as Corby and Barnsley, the proportion is half that or less. Moreover, the former are five times more likely to go on to university and then to good jobs in London’s diversified, vigorous economy. These are devastating figures.

Yet what is happening in Bristol, Manchester and the wider north-west and parts of the West Midlands is important. They have their share of economic and social “coldspots” – small towns that have never had the leadership, opportunity or support to diversify away from their 18th and 19th century industrial legacy – but they have fewer than their counterparts on the east of the Pennines. Indeed, the maps the Social Mobility Commission published in its state of the nation report last December show disproportionate disadvantage in the east – where the Brexit referendum was won. (After the report’s publication, all the members of the SMC resigned in protest at government inaction; tellingly, they have yet to be replaced.) This is the part of England with more “left behind” rural areas and more towns that are just not big enough or well-connected enough.

Cities have always been the load-bearers of economic and social advance: agglomerations of people are the source of creativity and scientific experimentation; they also create demand and then supply that demand. Cities are ever more important, but they need to be big – at least 2 million in population by some estimates –to create the scale on which diverse economies depend. London’s advantage, above all, is its size, although it has benefited hugely from an undeclared industrial strategy favouring financial services, the creative industries, its transport and, most recently, its education system. Being the capital doesn’t hurt either, while membership of the EU has attracted hundreds of companies to locate their headquarters there.

Many smaller towns have never been able to diversify away from their 18th and 19th century industrial heritage. Photograph: Christopher Thomond/The Guardian

Birmingham and Manchester, England’s next biggest cities, need to be bigger and governed as regions to capture these agglomeration effects and organise strategies better to support themselves economically and socially. Which is what they are doing. Manchester, under its visionary city leader, Howard Bernstein, began its progress 20 years ago; now it has a metro mayor. Whether through its universities, its Premier League football clubs, its creative industries and its reviving hi-tech manufacturing sector, Manchester is an exemplar of what a diversified city looks like. When linked to London and Birmingham via HS2, and to Liverpool and Leeds via HS3, it will do better still.

The West Midlands is beginning to get its act together under its new metro mayor. The “Midlands engine” is as important a symbolic rallying cry as the “northern powerhouse”: one of its cornerstones will be hi-tech manufacturing, a key reason why it is mobilising to protect the vital independence of one of its major manufacturing companies, GKN, threatened by an American asset-stripper. Equally, Bristol, under its mayor, is aiming to build on the Silicon Gorge effect and create a great “western powerhouse super city-region” with Cardiff and Newport.

The huge threat to all three regions – and even more for the regions in east England – is leaving the EU, with which all have massive trade links. The government reckons, in leaked estimates, that cumulatively over the next 15 years Brexit will mean England’s regions on average will grow by between 13% to 16% less than they otherwise would. The west will be in better shape to take the hit, but for the east, already flailing, it will be disastrous.

Attempts in Yorkshire, the East Midlands and the north-east, apart from Teesside and North Tyneside, to create new governance structures are perennially killed off by internecine, self-destructive local rivalries. Inside the EU, we could turn a corner; outside, the prospect is of a further slide into even crueller regional inequality. Better to stay and end today’s reality that place is destiny.