1. ITV Report

Why is it so hard to know who owns the United Kingdom?

These three men own almost one per cent of the United Kingdom's land. Credit: Bestseller / PA

Tracking the history of land in the United Kingdom throws up some unlikely origins to wealth.

Did you know that Britain's richest landowner has the marriage of a parliamentarian to a 12-year-old bride to thank for his £10.1 billion property empire?

In 1677, 21-year-old Sir Thomas Grosvenor received around 500 acres of what was then meadows to the west of London in a wedding to child heiress Mary Davies.

His modern day descendent is the Duke of Westminster, who at 28 inherited the Grosvenor Estate - which has expanded far beyond the prime London neighbourhoods of Pimlico, Mayfair and Belgravia - after the death of his billionaire father in 2016.

Hugh Grosvenor, centre, inherited the £10.1 billion family estate at 28. Credit: PA

He is just one of 11 people and organisations who own seven per cent of the UK - a combined area bigger than Northern Ireland.

So how much of the country is inherited, what does the royal family own and why is around 13% of our green and pleasant land still unaccounted for?

While his estate extends across the world, the Duke of Westminster holds 133,100 acres - or 0.22% - of the UK, including parts of Scotland and North Wales.

It means the Cheshire-based landowner is the 14th richest person in the UK, according to the Sunday Times Rich List, yet he's only the 11th biggest stakeholder of land.

Who owns the most land in the United Kingdom?

The individual with the most land in Britain isn't even British - or a member of the monarchy.

He's Danish retail magnate Anders Holch Povlsen, the billionaire fashion tycoon behind online clothing retailer Asos, along with shops Jack & Jones and Vera Moda.

Anders Holch Povlsen owns a large area of Scotland - and has ambitious plans. Credit: Bestseller / Instagram

Povlsen recently moved to the top of the UK landowning list after buying up a vast stretch of the Scottish Highlands and a string of historic estates.

Denmark's wealthiest man was also in the news for tragic reasons earlier this year.

He and his wife lost three of their four children in the Easter Sunday terror attacks in Sri Lanka.

Povlsen holds 221,000 acres (0.36%) of the UK and his plans for them have drawn criticism.

His intention is to return what is mostly plots of boggy marshland and mountainous terrain to nature and rewild the area over the next two centuries with the controversial re-introduction of lynx and wolves.

Who was the previous biggest landowner?

The Dane narrowly overtook the previous land title holder the Duke of Buccleuch.

The tenth holder of the hereditary title also owns a significant share of land in the Scottish borders.

The Duke of Buccleuch and his family seat, Bowhill House. Credit: PA

According to his estate's website, his holdings total more than 213,000 acres, meaning he's responsible for around 0.35% of the UK.

It means the three men mentioned so far, the Dukes of Buccleuch and Westminster and Mr Povlsen, together own almost 1% of the country's land.

That may appear insignificant, but it's the size of Warwickshire.

While they're the leading individual landlords, private organisations continue to hold the largest plots of the country's land.

The Forestry Commission has 2.2 million acres, while the National Trust owns more than 800,000 acres, taking into account lands held by its Scottish brand.

Other major players include the Ministry of Defence, the Crown Estate and the Royal Society for the Protection of Birds.

How much land does the Royal Family own?

The Queen privately owns almost 20,000 acres of land in the UK, which accounts for around 0.03% of land in the country.

The Duchy of Cornwall, which is headed by Prince Charles, operates a series of estates sprawled across 23 counties.

The 130,000 acre estate isn't subject to corporation tax and has a history dating back to 1337.

The royal family own less of the UK than you might think. Credit: PA

The Crown Estate, which is owned by the Queen for as long as she is on the throne, also has extensive assets, including London's Regent's Street.

In fact, it has more than 240 assets inside the M25 alone.

Then there is the rest of the country, with land and properties stretching across the breadth of England, Wales and Northern Ireland.

These are a diverse pick; taking in wind farms, shopping parks and restaurants.

Why is some UK land not listed?

While most land is accounted for, nailing down exactly who owns what in the UK is still an ongoing process.

The Domesday Book, drawn together in 1086, was the first comprehensive attempt to record the ancient fiefdoms of the kingdom.

William the Conquerer's land list enterprise may now be hugely outdated but it has still not been entirely updated.

William the Conquerer's ambition behind the Domesday Book was to work out taxes he was owed. Credit: PA

While land rules have evolved, it took until the late 1990s for the need to register sales of land to pass into law.

That means parcels of land which have not changed hands since this date have still not been recorded.

The ownership records for England and Wales held by the Land Registry, which has listed landowners since 1862, only cover 87.03% of the land mass.

It means just under 13% of England and Wales remains unaccounted for.

And it's not just small verges and greens that are below the registry radar.

What is missing and why is it so hard to know who actually owns the United Kingdom?

There are some famous sites which aren't documented, including Kew Gardens - ironically a site close to the current home of the Domesday Book - and even the Houses of Parliament.

According to the research pulled together by author Guy Shrubsole, The Crown Estate has registered an interest in the Westminster property, but isn't down as the official owner of the entire building.

"It's very hard to find out who owns the United Kingdom - partly because of the links between land and power," Mr Shrubsole told ITV News.

The author of Who Owns England? is particularly focused on the imbalance in ownership.

Kew Gardens, near the home of the Domesday Book, isn't registered with the Land Registry. Credit: PA

"All told, members of the aristocracy own around one third of England - that accounts for around 800 people," he said.

He further estimates - after researching land records, Freedom of Information requests and "rooting through the back pages of council websites" - around 1% of Britain's 66 million strong population own half the country.

This landowning elite, he says, is made up of new money individuals, bankers and those wealthy enough to buy land to sit on.

Mr Shrubsole is critical of the way some apparently play the registry system while declaring land ownership.

"Even if land is sometimes registered, it might be with a company based off-shore or a trust - and people hide behind that," he said.

"Secrecy in the land market has helped money laundering and pushed up prices of property in London. It's a safe haven for dirty money coming into the country."

Who owns the water?

If it's hard to know who holds all the land, the ownership of the water around the British Isles is a little clearer.

Possession of much of the liquid assets is divided into the hands of 10 companies in England and Wales.

United Utilities is by far the largest owner of water in England and Wales. It has 141,000 acres to its name.

In total, more than 420 acres of land are owned by water companies in England and Wales.

Around the country, the seabed is owned by the Crown.

Thirlmere Reservoir in Cumbria is owned by United Utilities. Credit: PA

Since 1760, the income of the Monarch has been surrendered to the government, with the financial affairs managed by the Crown Estate Commissioners.

The remit extends some 12 nautical miles off shore, and includes much of the foreshore.

The remainder is in a mixture of public and private ownership.

To complicate matters further, various government bodies have sovereign rights over marine resources to the edge of the continental shelf and the 200 nautical mile limit.

This doesn't apply to Shetland - off the northern coast of Scotland - where the Crown lays no claim to the foreshore.

Nor does it lay claim to much of the foreshore around much of neighbouring Orkney.

What about when people have to give up land?

Widespread reclaiming of land took place in the world wars of the 20th century to support military efforts.

There is no single source or comprehensive list of what was taken by a range of different government departments.

The Ministry of Defence still owns huge areas of land in Wiltshire now, as shown on the map of its property in the south of England.

Imber, on Salisbury Plain, is one of the locations owned by the MOD - as shown on the map. Credit: MOD / PA / Guy Shrubsole

One example is the village of Imber on Salisbury Plain.

Residents were evicted in 1943 to support the war effort; allowing American troops preparing for an attack on Europe to train.

But more than 60 years on, the land hasn't been returned to those who called it home.

Instead, people are allowed to visit Imber on designated days.

It's yet another quirk in the often strange story of how the land of the United Kingdom came to be divided up.