When Rosie Duffield stunned the political establishment by winning Canterbury for Labour at last year’s snap election, it slotted neatly into the “youthquake” narrative of the time.

The base for two universities, the Kentish cathedral city turned red for the first time on a gigantic swing from the Conservatives, for whom it had served as an impregnable fiefdom even in the wipe-out years of 1997 and 1945. It seemed self-evident that the students had taken the seat for Jeremy Corbyn.

Subsequent research has cast doubt on the youthquake theory, with the British Election Study indicating that voters in their 30s, not their 20s, were critical to Labour’s election advance.

And research published this spring by the political consultant Ian Warren reinforced the importance of those on the cusp of middle age.

Warren identified large movements of people in their 30s and 40s out of London and into the Home Counties and elsewhere in southern England, driven out of the capital by unaffordable housing costs.

Here they settled in what were often Tory-held commuter towns and regional hubs—and brought their liberal outlooks with them.

Polling by Warren’s consultancy, Election Data, found these ex-Londoners who had left the capital since 2013 were even more pro-Remain than the Londoners they left behind.

The ex-Londoners recorded a hefty 7 point swing from Tory to Labour between 2015 and 2017—contributing to a 10 per cent rise in Labour’s vote share across southern England and East Anglia.

One of the main recipients of these ex-Londoners was Canterbury.

Seeing the long-term picture

The electoral impact of this trend is not uniform. The Conservatives once more clung onto Thurrock, while defectors from Ukip maintained Eleanor Laing’s solid grip on Epping Forest.

Huge entrenched Tory majorities prevented the Corbyn surge from turning Surrey seats like Esher and Walton or Reigate into marginals.

Each of these seats has seen thousands of ex-Londoners move in—but with very different electoral consequences last June.

The Labour conveyer belt

However, the long-term picture seems clear: Labour is on the march in southern England. Older Tory diehards will die out over time, replaced by streams of youngish liberals.

Warren argues that unless the Conservatives can resolve the imbalances that lead to London sucking in students from the under-invested Midlands and North, and spewing them out across southern England via the London housing bubble, “there will always be a conveyor belt of [Labour-friendly] twentysomethings using London as a footstool to a home in the south-east.”

Once-safe Welwyn Hatfield could already fall to Labour on a good night. (That’s Grant Shapps’ seat, in case you’re wondering just how good such a night would be.)

A plot twist in Canterbury

Warren’s research is excellent and makes for fascinating reading. But tempting though the resulting narrative is, there’s a plot twist that’s missing.

As Warren notes, these ex-Londoners are often university-educated young professionals in middle-class jobs—natural Tory targets.

It is often argued that the swing of these ABC1s towards Corbyn’s Labour is due to their inability to get on the housing ladder, that you cannot have “capitalism without capital.”

But is this capitalism without capital? While London’s housing bubble may have driven these people out of London, what happens when they land?

We cannot say for certain how many of these ex-Londoners are renting and how many have bought less unaffordable homes.

But what we can see is that for those who have bought homes in Canterbury, the average value of their house rose 37 per cent between 2013 and 2017.

Of course, later arrivals (and locals) will find it hard to avoid the private rental sector if this goes on too long. Nor do we know how many purchases are by landlords and speculators.

But over the next few years, some of these new Labour voters are going to find themselves sitting on a growing asset.

The national picture

This isn’t just about ABC1 ex-Londoners either. People who recently bought homes in Portsmouth (where Labour gained a seat last year), or Clacton (Ukip’s old heartland), or Corby (a key Midlands marginal) are seeing solid house price growth.

Northampton, where both seats are now Tory-held marginals, has seen house prices rise by a third and transactions rise by a fifth since 2013.

The housing market may have maxed out in London, and landlords may be crawling over penthouse blocks in central Manchester, but outside these hotspots, every year, people are buying houses and finding their capital grows.

A slippery road for Labour

This doesn’t automatically create Tory voters. Brexit is a wedge issue, for one. So are schools and hospitals. And private sector tenants in cities like Brighton, Cambridge and Bristol are unlikely to become enamoured towards the Conservatives any time soon.

But this is nevertheless a slippery road for Labour to navigate.

If, away from London-based headlines, young professionals and families are seeing their housing wealth grow, then the property taxes so beloved of progressive economists and potentially key to enabling Labour to go beyond its 2017 spending pledges—the land value tax floated in Labour’s manifesto, or council tax revaluation, or inheritance tax reform—could be the black ice the party doesn’t see until it’s too late.

Because while these newly home-owning thirty-somethings may be socially liberal internationalists, money always talks at the ballot box eventually.

Just ask the Baby Boomers.