“The ownership of land,” wrote the 19th-century radical economist Henry George, “is the great fundamental fact which ultimately determines the social, the political and … the moral condition of a people.”

Who owns land matters. Landowners get to choose how their land is used, and that has big implications for almost everything: where we build our homes, how we grow our food, how much space we set aside for nature. Owning land confers wealth, status and often political power.

Margaret Thatcher’s ambition was to create a “property-owning democracy”. But like many members of Generation Rent, I don’t own a single square inch of the country of which I am a citizen. Even homeowners own only a small fraction of our island: urban areas cover just 10% of England and Wales. So, then: who actually owns this place? That’s what I’ve set out to investigate with my blog, Who Owns England?. I started it last summer, post-referendum, determined that if Brexit really meant “taking back control of our country”, then I’d like at least to know who owns it.

But the answer has turned out to be fiendishly difficult to find. It’s taken dozens of freedom of information requests and hours of poring over maps to even begin piecing together the jigsaw. I now know that the Ministry of Defence owns 750,000 acres, that the aristocratic Grosvenor Estate has 140,000 acres, and that grouse moor estates cover an area of England the size of Greater London. It’s very clear that land ownership in England is concentrated in the hands of the wealthy few: the investigative journalist Kevin Cahill has estimated that just 36,000 individuals own half of the UK’s rural land. But no one seems to have the full picture.

Understanding who owns this country has been a utopian project for at least a century and a half. In 1872, in an effort to disprove radicals’ claims that only a tiny elite dominated the landed wealth of the nation, Lord Derby – a major landowner himself – asked the government to undertake a proper survey. The Return of Owners of Land – or “Modern Domesday”, as it became known – was the first comprehensive assessment of land ownership in Britain since William the Conqueror’s swag list after the Norman conquest. But far from dousing the demands of the radical land reformers, the survey lit a fire under the issue.

The Return showed that just 710 aristocratic individuals owned a quarter of the entire country. Popularised by the author and socialite John Bateman in a bestselling book, The Acre-Ocracy of England, who owned land suddenly became the talk of the town. But it wasn’t just the gentry keeping up with the Joneses; land reform had become the political issue du jour. After all, this was a time when you couldn’t vote unless you owned property; when tenant farmers were struggling under a severe agricultural depression; and when the urban poor were crammed into overcrowded slums, at the mercy of grasping landlords.

Into this potentially revolutionary situation walked Henry George, an American economist with a radical new solution for the ills of the world. He proposed a land value tax – a tax on rent-seeking landowners who got rich simply by owning land in valuable locations and allowing it to accrue in value. In order to levy such a tax, it would first be necessary to survey all landowners and carry out a valuation of their property.

George’s utopian ideas inspired a generation of radicals, spanning all parties – from socialists to Liberals and even radical Tories such as Theresa May’s political inspiration, Joseph Chamberlain, who ran for election on the promise to secure for all farmers “three acres and a cow”. Yet English land reform was a dream that soon faded. The Modern Domesday was forgotten, George’s land tax dismissed as too radical, and all that the land reformers achieved was some legislation to create allotments. (A later push for land reform in the Edwardian period was first defeated by the landowning interest in the House of Lords and then cut short by the first world war.)

But spool forward to the present, and there are plenty of fresh reasons for wanting to know who owns our land. We face a housing crisis of epic proportions, caused at least partly by housing developers’ “stranglehold” on land supply, as the communities secretary puts it. As Brexit looms, we need to completely overhaul our broken system of farm subsidies, which for too long has rewarded landowners simply for owning vast estates, rather than providing public goods.

We face the existential threats of climate change and a potential mass extinction event, both demanding that we rethink our relationship with the land in order to restore nature and make ourselves more resilient against worsening flooding. And if we’re to reduce spiralling inequalities in wealth, we might well start by addressing landed wealth. Land, after all, is inherently scarce and prone to monopoly; as Mark Twain once observed, “they aren’t making it any more”.

Fixing all of these requires first knowing who owns our land. It’s something that should unite the most radical activist with the mildest reformer. Whether you’re a conservative aspiring to create a property-owning democracy, an anarchist who believes all property is theft, or a Georgist campaigning for land value tax, the first step is finding out who owns it all currently.

So if the answer to who owns England isn’t available from existing public data, how to find out? Well, the Victorian land reformers did leave us one other legacy: the Land Registry, whose job it is to gradually register who owns all land in England and Wales. Yet 150 years after it was founded, it’s still not completed its task – around a fifth of all land remains unregistered. And though the Land Registry has thankfully just survived a government attempt to privatise it, it remains a very closed public service: you have to pay £3 just to find out who owns a single field. Paying to find out who owns the whole country would cost a fortune.

It’s high time, therefore, to open up the Land Registry and mandate its completion. In the era of the internet, open data and GIS mapping, it’s frankly archaic for the Land Registry to hide its secrets behind a paywall. If Companies House can drop its search fees and open up its wealth of information for free, so can the Land Registry.

The government’s recent housing white paper heralded some welcome steps in this direction – announcing that the Land Registry would soon make freely available its datasets on land owned by UK companies and offshore firms. But that’s only a fraction of the total. Aristocratic families, who almost certainly still own the great majority of England, will be exempt – since their huge estates are invariably registered in an individual’s name, if they’re registered at all.

“Who owns England?” is a beguilingly simple question, but finding an answer to it would be genuinely utopian. Knowledge, after all, is power: and knowing who owns our land would be a first, crucial step towards really taking back control of our country.