King Charles receives urgent request for intervention as £800m development looms

"Since the Crown leases land to the duke, the Crown must be consulted," Mr Summer stated in his letter to the monarch.

He argues that "leasing and giving ownership of Blenheim land to a third party who will directly enjoy financial benefits is against the 1705 Queen Anne Act."

The campaigner has asked the Crown to "enforce its ownership of the Blenheim Estate as Queen Anne intended."

The proposed development would span nearly 3,500 acres across Botley, Woodstock and Kidlington in Oxfordshire.

The Planning Inspectorate is currently examining the scheme and will make recommendations to Energy Secretary Ed Miliband within six months.

Mr Summer's legal argument centres on his interpretation that the Blenheim Estate lacks official ownership of the land under the 1705 Queen Anne Act.

He maintains the Act stipulates the land should not be used for purposes beyond those of the duke.

"I therefore humbly ask that the Crown steps in to enforce its ownership of the Blenheim Estate as Queen Anne intended and refuses the Blenheim Estate land to be handed over to any third party," Mr Summer wrote.

The arguments were recently presented at a Planning Inspectorate hearing in Oxford, which has requested further clarification from Blenheim.

The King, who has championed environmental causes throughout his life, has called for rapid expansion of renewable energy and aims to achieve net zero for the Royal Household by 2030.

His Majesty has already installed solar panels at Windsor Castle and developed a solar farm on a former horse grazing paddock at Sandringham.

Despite his known support for renewable technology, the monarch has not yet responded to the Botley West controversy.

Local residents have been actively campaigning against the plans, with Mr Summer motivated by his interest in the area's history to research the relevant parliamentary acts.

Professor Alex Rogers, chairman of Stop Botley West, said the letter has challenged "the idea that the developer can do whatever they want with the land."

The 12th Duke of Marlborough, known as Jamie Blandford, reportedly opposes the project.

The Duke is a member of Reform UK, which believes "productive land must be farmed, not be used for solar farms or rewilding."

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However, his influence over the estate remains limited following drug addiction issues and multiple prison sentences that led to him losing control of the family seat in 1994.

He is not a trustee of the Blenheim Palace Heritage Foundation, which operates the World Heritage site.

Despite the Duke's opposition, the estate itself backs the project. The development is expected to generate approximately £1,000 per acre annually throughout Photovolt's 40-year lease of the land.

Mark Owen-Lloyd, director of Photovolt, defended the project, stating: "Should the project be granted consent, Photovolt will become one of many tenants of the Blenheim Estate, who have leased their land for centuries."

He added that "the restrictions apply only to the World Heritage Site that is Blenheim Palace, which will of course have no solar panels installed on it."

A Blenheim Estate spokesman said: "We are aware of the comments made during the public examination which are not correct in relation to this project."

The controversy follows Mr Miliband's approval earlier this year of Heckington Fen Solar Park in Lincolnshire, owned by Labour donor Dale Vince's company Ecotricity, which has donated £5.4 million to Labour since 2021.