Buckingham Palace insists royal estates are sustainable as Channel 4 accuses King Charles and Prince William of making millions from wind farm firms and polluting mining operations

Buckingham Palace has insisted that the royal estates are sustainable as Channel 4 Dispatches airs a damning investigation into the its 'secret millions'.

The programme, which will air tonight at 8:10pm, examines the cost to the nation of the Duchy of Cornwall and the Duchy of Lancaster – fiefdoms which date back to medieval times.

In the show, seen by MailOnline, it claims that King Charles and Prince William taken millions from cash-strapped public services and charities, broken government rules by renting out properties with poor energy efficiency ratings and strike controversial deals which fly in the face of their supposed environmental principles.

The estates have helped make the British royal family one of the richest in the world, generating almost £50 million for the King and the Prince of Wales in the last year alone.

However, Buckingham Palace has hit back claiming both estates are sustainable and not funded by the taxpayer.

The Duchy of Lancaster, controlled by the King, states that 'is completely self-financing and does not rely on any taxpayers' money' and the Duchy of Cornwall, helmed by Prince William , says that 'it is not a public body, nor is it funded by the taxpayer'.

Examples given from their investigation include an announcement last year that the Duchy of Lancaster was 'delighted to help and support' Guy's and St Thomas' NHS Trust as it sought a home for its new fleet of electric ambulances.

What the Duchy didn't reveal was a deal to house the vehicles in one of its London warehouses is worth £11.4 million over 15 years. The same site was previously leased to the Metropolitan Police, at a cost of £1 million per year.

Meanwhile, the Duchy of Cornwall has signed a £37 million deal to lease Dartmoor Prison to the Ministry of Justice; charged the navy more than £1 million to build and use jetties and moor warships; made more than £600,000 from the construction of a fire station and stands to get nearly £600,000 from rental agreements with state schools over the lifetime of six different leases.

Baroness Margaret Hodge, a former Labour MP and chair of the public accounts committee, told the programme: 'In the court of public opinion, you always have to be cleaner than clean.... And if there is a question mark over a charity that has a royal patronage and therefore gains extra income, then that income is then used pay rent back to the royals, it just doesn't feel quite right.'

Both the King and Prince William have warned about our responsibility to protect the environment.

The King has said: 'Unless we rapidly repair and restore nature's unique economy based on harmony and balance, which is our ultimate sustainer, our own economy and survivability will be imperilled.'

And William has added: 'The shared goals for our generation are clear, together we must protect and restore nature, clean our air, revive our oceans, build a waste free world and fix our climate.'

However, Dispatches alleged that some of their estates' investments threaten the natural world they claim to protect. Collectively, the Duchies own thousands of mineral rights – and have cashed in by striking deals with controversial mining companies for sites across the country.

In Hingston Down, an area of outstanding natural beauty, the Duchy of Cornwall leases land to one of the biggest polluters in Europe. Duchy officials have allowed the company to blast for stone chips for the road and building industries.

It is also allowing a drilling company to search for minerals across Cornwall, including at Wheal Vor, another area of outstanding natural beauty where waters have been contaminated by years of mining.

Working with the Mirror newspaper, the programme found that scores of properties being rented out by both Duchies failed to comply with minimum energy efficient requirements for landlords – leaving some tenants shivering in homes blighted by black mould and struggling with fuel poverty.

It detailed how 14 percent of homes leased by the Duchy of Cornwall and 13 percent by the Duchy of Lancaster have an energy performance rating of F or G. Since 2020, it has been against the law for landlords to rent out properties that are rated below an E under the Minimum Energy Efficiency Standards regulations.

Many failing properties emit huge amounts of carbon, which again impacts the environment.

One tenant said: 'It gets miserably cold in winter, I can only heat two rooms in my home. The Duchy does not understand.'

A second added: 'The house is cold, and it is a struggle but there is nowhere else to live here. They are not good landlords. When the wind blows the curtains start swinging. There's no heating upstairs at all.'

The King won praise last year when he asked for vast profits from offshore wind farms on the separate Crown Estate be used for the 'wider public good' rather than to help generate more funds for the royals.

Crown Estate profits are used to calculate the royals' annual sovereign grant – the taxpayer funded allowance which pays for the monarch's official duties.

But despite this promise, the Duchy of Lancaster has continued to make money from wind farms.

Rent from five leases allowing cables to cross the King's land on the Lancashire coast will earn a minimum of £28 million over their lifetime.

A spokesperson for the Duchy of Lancaster said: 'The Duchy of Lancaster operates as a commercial company, managing a broad range of land and property assets across England and Wales.

'It complies with all relevant UK legislation and regulatory standards applicable to its range of business activities.

'The Chancellor of the Duchy of Lancaster is responsible to the Sovereign for the administration of the Duchy. However, he/she delegates certain functions, particularly those regarding asset management, to the Duchy Council. While His Majesty The King takes a close interest in the work of the Duchy, the day-to-day management of the portfolio is the responsibility of the Council and executive team.

'The Duchy has made a number of key environmental improvements in recent years, delivering a significant increase in the number of A+, A and B EPC ratings awarded to our properties as a result of refurbishment or restoration works. Currently, over 87 per cent of all Duchy let properties are rated E or above. The remainder are either awaiting scheduled improvement works or are exempted under UK legislation.

'The financial and environmental performance of the Duchy is disclosed each year in our published Report and Accounts which are independently audited and freely available on the Duchy of Lancaster website. His Majesty The King voluntarily pays tax on all income received from the Duchy, as did the late Queen Elizabeth II.'

A Duchy of Cornwall spokesperson said: 'The Duchy of Cornwall is a private estate with a commercial imperative which we achieve alongside our commitment to restoring the natural environment and generating positive social impact for our communities.

'Prince William became Duke of Cornwall in September 2022 and since then has committed to an expansive transformation of the Duchy. This includes a significant investment to make the estate net zero by the end of 2032, as well as establishing targeted mental health support for our tenants and working with local partners to help tackle homelessness in Cornwall.'

On the issue of mining, the spokesperson said that the Duchy was 'acting responsibly and in a sustainable way' to the government's industrial strategy, which encourages investment in domestic sources of minerals.

The spokesperson added: 'The Duchy is engaging with the critical minerals industry in Cornwall to respond to the UK Government's Industrial Strategy.

'We have granted a number of three-year exploration licences and all licensees must ensure that their activities are in strict accordance with statutory requirements and meet high environmental standards.'

Dispatches is a current affairs programme that covers a wide range of topics including, health, international affairs, and politics.