The most remarkable, and perhaps remarked upon, aspect of the 2017 general election was the political division between the generations. The young overwhelmingly voted Labour while the over-55s, particularly over-65s, voted Conservative. So far, this age-based political polarisation is getting more pronounced as the general election campaign goes on.

It’s a cliche that people get more conservative as they age, but this phenomenon is not natural or predetermined: the UK’s generational chasm has material causes that emerge from long-term trends. In the 1983 election more 18- to 34-year-olds voted Conservative than Labour, so what changed?

Margaret Thatcher’s sell-off of social housing in the 1980s started a rise in house prices, which was then turbocharged by the deregulation of finance. The post-2008 collapse in home ownership among younger people has helped produce a sharp divide in who owns property. Old and young are voting differently because they now have different material interests.

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Those over 55, who own their own home and have pensions invested in stocks and shares, have found their interests increasingly aligned with the performance of finance and real estate. If the stock market booms then the value of their pensions increase; if property prices are high they will feel wealthier and can borrow more from their banks. This is not true for the young who, cut off from home ownership, are dependent on wages and welfare, which have stagnated and been cut over the last decade.

Post-2008, government policy has favoured finance and inflated asset prices, from the hundreds of billions spent bailing out the banks to the tsunami of free money (quantitative easing) produced by the Bank of England for the financial sector. Incredibly low interest rates have, by making it unattractive to keep money in the bank, added to a glut of liquid cash looking for a home. Yet business investment has been relatively flat. Why invest in new technology and job-producing industry when higher returns can be found speculating on real estate and stocks? It’s little wonder that older people are tending to vote for more of the same – but this low-growth, low-interest, high-asset price world we’re stuck in offers little hope for the young.

So should we rage against the elderly as selfish monsters feasting on the impoverished futures of their descendants? Of course not. In the absence of the prospect of structural change, voting to protect the inheritance you leave behind is a viable way of looking out for your grandchildren’s interests.

With this problem in mind I read the Labour and Conservative manifestos to see if they planned to bridge the generation gap. While pensioner benefits will be retained, Labour has promised a levy on holiday homes and a reversal of Tory cuts to the inheritance tax paid by the wealthiest pensioners. Even more importantly, the pledge to build a million homes in a decade will improve the supply of housing. Alongside increased rights for renters, this will inevitably lead to house price deflation. These policies would be fantastic for Generation Rent but would adversely affect the financial interests of many pensioners.

This might reaffirm many older people’s rejection of Labour – but the manifesto also contains the offer of a very different model of ageing. Reversing the state pension age to 66 will be attractive to the middle-aged, who were seeing their retirement retreating into the distance. Also, the increased spend on the NHS should be attractive to the elderly, who use it most. But the key proposal is free care for the over-65s and a £100,000 cap on personal contributions to other costs of a lifetime’s care. This directly attacks the idea that equity withdrawal from expensive homes is the only way to guarantee the care the elderly need in old age.

In contrast, the Conservatives’ Brexit-centric manifesto promises little and has the budget to deliver even less. In the medium and long term, the political age gap is an existential threat to the Conservative party. The concentration of property ownership is preventing the creation of new Tory voters to replace those who die. Brexit may temporarily paper over the cracks but, beyond this election, the manifesto offers only voter ID laws, which are likely to affect low-income and minority groups disproportionately, as the hint of a longer-term solution.

The Conservatives clearly do not aim to convert anyone new, so the fate of the election rests on the different age groups’ reaction to Labour’s offer. Will it tempt a large enough slice of the silver vote out from behind the walls of their overvalued properties into an alliance with the demands of the young? Will the green new deal and increased minimum wage enthuse enough under-35s to register and vote? The answer depends on the prevailing sense of political possibility – and that, in turn, will be decided, beyond all other things, by the number of young canvassers flocking to the doorstep on behalf of Labour. Young people have a world to win, but I hope they can bring the older generation with them.

• Keir Milburn is a lecturer in political economy and organisation at the University of Leicester, and author of Generation Left