That has raised a potentially awkward question.

How does the royal family fund itself in the 21st century?

It's not something the royal family like to publicize, but here's what we know about their main sources of income.

There's something called the Duchy of Lancaster, almost 45,000 acres of commercial, agricultural, and residential properties in England and Wales owned on behalf of the Queen.

The Duchy comprises around US$710 million in net assets, which is mostly held in trusts.

The profit made by these sites, castles, historical land, and property at the heart of the capital goes directly to the Queen and no other member of the royal family.

Last year, it netted her 20.7 million pounds or US$ 26.7 million.

Next up, there's the Duchy of Cornwall.

Like the Duchy of Lancaster, the Duchy of Cornwall is a private estate, except this one is owned on behalf of Prince Charles.

In 2019, the Duchy of Cornwall paid Charles over US$28 million on almost US$1.2 billion of net assets.

Though the profit goes directly to Charles, both Prince William and Prince Harry receive money from the Duchy through their father.

Last year, they got around five million pounds in total from Prince Charles' fund.

There are questions whether Harry will have to give up this source of funding if he is to become financially independent.

Then there's the family's personal wealth.

That's the investments, companies, and private estates that various royals hold.

The value of this and what they yield in income is undisclosed.

For instance, the Queen privately owns the Sandringham Estate.

How much the royal family gains from this income is unknown, but royal biographers estimate the royal family's wealth is in the millions, not the billions.

That means royals in the 21st century might be rich, but they're not super-rich.

In a move to keep this revenue stream going, the Duke and Duchess of Sussex, Harry and Meghan, have applied to trademark Sussex Royal, a brand which will cover a whole host of items ranging from socks to greeting cards.

The largest source of income for the royals is government money through a thing called the Sovereign Grant.

In the 1700s, the monarchy handed over revenues from swathes of land to the government known as the Crown Estate.

Each year, the government pays a percentage of the profits made on those assets back to the monarchy.

That annual income is known as the Sovereign Grant.

Last year, it amounted to almost US$ 107 million and it paid for royal duties and the maintenance of palaces including Buckingham Palace.

Meghan and Harry don't appear to be ready to give up all of those funds.

The couple's website, sussexroyal.com, said that they expect to keep state-funded security.

And they want to continue to live in a cottage owned by the Queen and refurbished at a cost of US$3.1 million to the taxpayer.

The fact that such a large proportion of the royal income effectively comes from taxpayers is part of the reason why there is such public interest in this decoupling.

The monarchy has spent years trying to rise above such earthly matters as how they are actually paid for.

And that's one of the reasons why the Meghan and Harry debacle is leaving the monarch feeling uncomfortable.