Another thing not detailed in the report is what proportion of the Privy Purse income has been spent by the King personally and what proportion of it has been spent for official royal duties.

This matters because the King only voluntarily pays tax on income spent personally, meaning the King can effectively deduct royal business from his tax bill.

The King also does not pay tax on the Sovereign Grant, which is money paid from the Treasury to the Royal Household to pay for official duties.

This system is a bit like how a self-employed person can file expenses on their self-assessment tax return for things like uniform or training.

Except that the King has two tax-free ways in which he can he can fund official duties.

Also, what counts as official duties is very different from what a regular self-employed taxpayer can expense.

For example, the untaxed Sovereign Grant can be used to fund the staff costs and running expenses of the King’s official household while untaxed official duties that can be paid by Privy Purse include the personal income of working members of the Royal Family.

The Keeper of the Privy Purse, James Chalmers, said: “While Royal finances can sometimes appear complex, the underlying system is clear in principle, structured in law and refined over time to ensure the Monarch can serve with independence, accountability and in the long-term interests of the nation.”