Let me take you inside one of the annual briefings about royal finances. A select group of journalists are summoned to the Palace and cloistered in a small room where they are handed a fat folder full of fascinating, and sometimes bewildering, figures.

You learn how much is spent on official duties, how much goes on travel and entertaining, what the laundry costs and even the outlay on things like flowers. It all seems extraordinarily open and transparent. And yet, the full picture has always been rather murky. We have never been told how much the monarch has paid in tax or how much was claimed as business expenses.

And, make no mistake, both the King and the Prince of Wales are at the head of multimillion-pound businesses: the Duchy of Lancaster, which stretches across about 45,000 acres of England and Wales, and the Duchy of Cornwall which covers a staggering 135,000 acres across 23 counties and, rather bizarrely, includes The Oval cricket ground. Each Duchy generates a profit of more than £20m a year, which is used as private income for the King and the Prince.

The news that King Charles has now decided to make his tax affairs public is therefore welcome.

The Palace has been at pains to make it clear that this is the King’s express wish. And that rings true because, as Prince of Wales, Charles did indeed reveal how much tax he was paying. For the year ending 2022, it was £5.89m. There has been no explanation thus far of why William has not been more forthcoming – especially as it’s understood he pays almost £7m – putting him in the top 0.002 per cent of taxpayers in the UK. Nothing to be ashamed of there – and it seems that he too is now set to publish his tax returns.