It’s often said that you can walk from Oxford to Cambridge without leaving land owned by the colleges. That’s almost certainly a myth. But as the Guardian’s recent investigation has revealed, they sure own one hell of a lot of land.

England is owned by a tiny number of people and organisations – and the Oxbridge colleges, with their 126,000 acres of land and property portfolios worth some £3.5bn, are among the largest institutional landowners. The Guardian’s analysis is the most comprehensive since 1873. But why has it taken so long to find out?

Land ownership remains one of England’s darkest secrets. When I started sending freedom of information requests to Oxford colleges back in 2016, asking them to reveal what land they owned, many were cagey. It seemed no accident that the colleges that were happiest to respond were also the ones who owned very little, while some of the richest, like St John’s (total property assets: £250m) refused point-blank to disclose the information. It’s taken huge persistence by investigative journalist Xavier Greenwood to unearth the full picture.

These latest revelations beg further questions about the responsibilities of our oldest universities to wider society. As places of learning first and foremost, Oxbridge’s admissions policies – and their shockingly poor performance in admitting students from more diverse backgrounds – has rightly attracted recent attention. But the colleges are also corporate bodies with huge purchasing power, whose investments also demand scrutiny. The fossil fuel divestment movement has made extraordinary gains in turning the spotlight on how universities are funding climate change, and successfully pressured many into ditching coal, oil and gas from their portfolios.

I believe equal scrutiny is now required on land ownership, in order to solve the housing crisis, tackle a catastrophic decline in habits, and reverse spiralling inequalities in wealth. Many landowners, by monopolising valuable land in prime development locations, may be unfairly profiting from the housing crisis by hoarding land in the hope that they can sell it for more in future.

How many of the fields and brownfield sites owned by Oxbridge are effectively land banks? Do the colleges’ property empires include any of the 60,000 long-term empty properties known to lie vacant across England and Wales? Where a college has sold its land to a developer, how many of these homes are genuinely affordable? On all these counts, Oxbridge might emerge blameless – but we can’t yet find out, because most of this information isn’t public. The colleges have not readily published full details of their landholdings, and the Land Registry’s datasets remain highly opaque and difficult to map.

The colleges might respond that they are businesses whose responsibilities lie in turning a profit and then reinvesting that in education and research, and whose investment decisions are commercially confidential. But the universities are public bodies in receipt of public funding, and the colleges are charities, with a particular social obligation towards future generations – the students they educate – and a wider responsibility passed down by history.

This historic inheritance includes large chunks of the land they own. That poses further questions – and ones that apply not just to the Oxbridge colleges, but all landowners. “Land … is the greatest of monopolies,” averred Winston Churchill, in a blistering invective penned during the battles over the “People’s Budget” of 1909, which threatened landowners with a land value tax. Churchill’s argument was that land becomes valuable thanks to the efforts of everyone – people who choose to live and work in a particular area; governments who invest in public transport and amenities to make such places attractive to live in. But it’s always the landowner who pockets a disproportionate amount of the increase in the value of such land.

The land owned by Oxford and Cambridge is just the tip of the iceberg. The Church Commissioners own some 105,000 acres of the country; the Duke of Northumberland owns at least 100,000 acres, nearly 10% of the county that gives him his title; the aristocratic Grosvenor Estate, besides owning 135,000 acres of farms and grouse moors, also has some of the hottest super-prime real estate in London. It’s no accident that Mayfair is the most expensive location on the Monopoly board: in real life, house prices there average out at a staggering £21,000 per square metre. The Grosvenors obtained Mayfair three centuries ago through an inherited dowry, when it was still fields; through a lucky roll of the dice, it’s now the basis of their £9bn fortune.

Churchill, in common with many liberals, socialists and even some radical Tories of his generation, believed that land ownership was a special case – a share in the country that brought with it particular responsibilities. Land is inherently scarce. It’s also the bedrock of the economy: the food we eat, the homes we live in, the natural world that supports human civilisation.

The idea that landowners should pay back some of the windfall gains they receive from rising land prices to wider society is something that all parties, in principle, now agree on. The Greens and Lib Dems have long believed in this, and Labour has made very encouraging recent strides. Even the Conservatives’ 2017 election manifesto included a pledge to ensure “communities themselves … benefit from the increase in land value from urban regeneration and development”.

But getting big landowners to accept their wider social responsibilities is going to take public pressure. What we need is a new movement on campuses – taking the fossil fuel divestment movement as its inspiration – to pressure universities into revealing their land and property investments, and encourage them to invest in housing that would be affordable to Generation Rent.

That could light the touchpaper of a wider movement to fix the housing crisis by addressing its fundamental driver – the value of land, and who owns it.

Guy Shrubsole blogs at whoownsengland.org