The Duke of Cambridge turns 30 today, and is therefore entitled to inherit his share of his mother's estate - thought to be worth roughly £10 million. So what will the fairly-newly-wed choose to spend the money on?
And will it make a real difference to a life that is already arguably pretty comfortable?
InheritanceWhen she died 15 years ago, Diana, Princess of Wales left almost £13 million in her will, including the cash left over from her £17 million divorce settlement. The experts have calculated that investments in the intervening years may have taken the total to £20 million.
The money was left to be split equally between her sons when they turned 25, but the executors of her will changed the age of inheritance after her death to 30. It means he will be £10 million richer by the end of the day.
Not too shabbyIt's a fairly hefty chunk of cash, and one that might make a bit of difference to any normal newly-wed man who earns a £40,000 salary as a search and rescue pilot, and is living in rented accommodation in Anglesey. However, there's nothing normal about the Royals.
Of course, it helps that unlike any other man in his position he didn't have to fork out a small fortune for his wedding - because we did that.
What will he buy?There has been plenty of speculation that he could spend the money building his own family home. If he chose to buy rather than build, his £10 million would stretch to some interesting places. He could opt for a Georgian five bedroom terraced house in Mayfair, or a five bedroom converted church in Richmond (which might raise a few eyebrows).
He'd be hard-pressed to spend the money in Anglesey, where an eight bedroom detached house with a pool and gym wouldn't cost more than a third of his fortune. And he could manage a home in the Highlands with its own loch thrown in.
However, disappointingly, a Royal aide told the Telegraph that he isn't in any rush to buy a home as he is weighing up another tour with the RAF's Search and Rescue force, which could mean moving base and throwing a house purchase decision into disarray.
Blowing it?With a home out of the window, he could choose to splurge the cash. This kind of sum would buy him something mid-range from the world's ten most expensive diamonds - such as The Heart of Eternity which is a 27.64 carats vivid blue heart-shaped diamond. Alternatively he could opt for all ten of the most expensive off-the-shelf supercars in the world, including the Bugatti Veyron Super Sports which costs more than £1.5 million.
Unfortunately, this kind of spending is fairly unlikely. The same aide also revealed the depressing fact that we're not going to see him going on any lavish spending sprees any time soon. Even his birthday party is said to be 'low key'.
However, there remains another option. He may yet choose to vary the will, to allow Prince Harry to pick up most of the inheritance - to take account of the fact that once his father becomes King, William will be given the Duchy of Cornwall - with a guaranteed income.
Should he become King, William can then go on to enjoy the insane levels of cash and assets of the monarch. The most recent valuation of the Crown Estate profits alone was £240 million - up from £211 million last year. This means the Queen will be entitled to an income of over £36 million this year (as she is allowed 15% of the value of the estate in income) - which starts to make £10 million look a bit paltry.