How much is the monarchy worth to Britain?

Britain's royal family -- and monarchist-loving Anglophiles the world over -- are celebrating Queen Elizabeth's 90th birthday Thursday. But some argue that the monarchy is an outdated institution and a drain on precious public funds.

Not so fast, says one London-based marketing company. Figures released by Brand Finance claim the monarchy will deliver a net profit of precisely 1.144 billion pounds to the U.K. economy this year alone. That's a cool 1.64 billion U.S. dollars. The total economic value of the British monarchy is more than $83 billion, Brand Finance estimates.

The "Firm," as the British royal family is sometimes referred to, helps drive tourism to the United Kingdom, generates surpluses from the Crown Estate, and helps boosts prices for products that carry the much-sought after "royal warrant," Brand Finance says. (The "warrant," by the way, is a seal companies can display on their products if they are among the annointed suppliers to the royal households - think Cadbury chocolate, Jaguars, Burberry, etc. Presumably, a royal warrant lets you charge a premium -- maybe even princely -- price for your products.)

Brand Finance says its final economic impact figures include the deduction of government costs, including security, palace maintenance and the so-called "Sovereign Grant," which this year came in at 37.9 million pounds (or $54.3 million).

"Brand Finance's research shows that from an economic standpoint at least, the royalists firmly have the upper hand. The Queen is exceptionally hard-working and respected; it will be interesting to see whether in due course Charles and William make as effective CEOs as Elizabeth," the company CEO, David Haigh, said in a statement.

As far as personal wealth goes, the queen is reportedly worth $425 million, Bloomberg's Billionaire Index estimated.

And while the royal family is still immensely rich, their financial circumstances have changed somewhat during the past few decades. In 1992, the queen agreed to start paying income taxes; in 1997, the government decommissioned the Royal Yacht Britannia, citing high operating costs; and at times, some members of the royal family have been been known to fly commercial.

The Sovereign Grant helps cover some of the monarchy's costs, including some palace maintenance, salaries and travel. As Sir Alan Reid, Keeper of the Privy Purse, has pointed out, the grant comes out to about 56 pence (or around 80 U.S. cents) per person, per year. If Brand Finance's math is right, that may not be a bad return on investment -- whether you're a monarchist or not.