But it emerged that as a tenant he had been intermittently sub-letting three cottages that were part of the property, which was thought to be for staff and at a below market rate, with Mountbatten-Windsor keeping the income.

The Crown Estate had told MPs that it did not have any oversight over how much Mountbatten-Windsor charged - and sub-letting was allowed as part of his lease.

But the MPs have recommended that in future the default position for such Crown Estate properties should be that such sub-letting should be banned, unless there was a specific exemption.

The Public Accounts Committee report also confirms what has happened since Mountbatten-Windsor's departure from Royal Lodge.

There was a payment of about £300,000 due to him for his early surrender of his lease, but because of "dilapidations" in the state of the building, there was a repair bill of £1.8m.

That meant the Crown Estate was owed £1.5m, which King Charles paid on his brother's behalf.

The watchdog's report also highlighted concerns about the level of rent being charged to non-working royals who had been given accommodation in three royal properties.

That was believed to be Mountbatten-Windsor's daughters, Princess Beatrice and Princess Eugenie, and Prince and Princess Michael of Kent.

A National Audit Office report had revealed earlier this year that Princess Beatrice and Princess Eugenie do not pay anything themselves for their accommodation in St James's Palace and Kensington Palace respectively.

The King pays their rent to the Royal Household from his own private income.

But the group of MPs were concerned about whether the level of rent on such properties for non-working royals was based on up-to-date valuations and recommended a more consistent approach to ensure value for money.

There was criticism too for the Crown Estate concentrating too much of its urban property portfolio in London and the south east of England, with MPs calling for more of a regional spread.

There were also warnings about how the Crown Estate's administration costs had increased significantly, at a time when MPs noted government budgets were under pressure.

The report said administration costs had risen by 129% since 2020-21 and that the chief executive, Dan Labbad's salary had risen by 106% over that time. In 2025-26 his pay package was worth £2.3m.

In response, a Crown Estate spokeswoman said: "The Public Accounts Committee report is an important part of our accountability to Parliament. We are considering its findings and recommendations and will respond to the Committee in due course."