Currently, there are only four serving HRHs (out of 13) who are anywhere under the age of 70, namely Edward and Sophie, the Earl and Countess of Wessex (both are 55-years-old) and William and Kate, the Duke and Duchess of Cambridge (37 and 38 respectively). (Princess Anne will only hit the big 7-0 in August but she is hardly a spring chicken.)
Enter stage left, Princess Beatrice and Princess Eugenie! And with them, a number of new headaches for the Queen to deal with.
This week, there have been a series of reports saying that the York women are going to be dragooned into the ranks of working royals to help pick up the slack.
On paper, it is a super plan.
They are bona fide Princesses, have drastically improved their taste in hats of late and proved to be all-round commendable people. They have actual jobs, nice blokes and have miraculously proven to be far less scandal-prone than their parents.
Over the years, they have earned growing public respect for the dignified way they deport themselves and actually building careers rather than just lolling around on damask chaises inside Kensington Palace buying fascinators by the dozen online.
Essentially, they are the royal reserve corps and they look like they are about to be called up for frontline duty. The Daily Mail's Richard Kay has reported that Beatrice and Eugenie have already been booked in to attend Buckingham Palace garden parties later this year.
But dragooning them into royal duty also poses a number of headaches.
Every appearance they make and every event they attend will revive talk about Prince Andrew.
No matter how hard Beatrice and Eugenie work and how diligently they accept posies and make small talk with retired Brigadiers over weak cups of tea, their very presence will sadly serve as a constant reminder of their father's alleged moral deficiencies and considerable public failures.
Prior to Christmas last year, there were reports that Palace courtiers feared that anti-abuse campaigners would line the public path the royal family walks along to attend church and might heckle Andrew. While it would be grossly unfair for Beatrice and Eugenie to ever be lumped in with their father's mistakes, it is not outside the realm of possibility that they could face a similar scenario.
Then there is the pesky money issue.
If Bea and Eugenie suddenly have to spend numerous days dashing around the country to do their bit – such as taking on the patronages for Badminton Wales and the Royal College of Ophthalmologists (just two of Andrew's 200 plus patronages) – it would surely make doing actual paid work quite difficult.
Thus, would they be forced by circumstance to quit? Working members of the royal family receive cash from the Sovereign Grant to pay for expenses and staff (of which the York women currently have none). I can't imagine the public reaction to more titled folks getting dosh from the government coffers would go down particularly well. (Ditto providing them with the Metropolitan Police protection officers they would be entitled to.)
Lastly, no matter how smart, charming and hardworking these women might be, their very presence at official events would serve as a poignant reminder of one of the Windsors' tougher periods in recent history.
If things get any tougher, it might be time for Prince Philip to come out of retirement.
Just don't let him drive himself.