Prince George and Princess Charlotte: Where are they in line to the throne?
One or the other of Kate and William's children will eventually ascend to the throne
Like many of us, the Queen is back at work after falling ill over the festive period and having to miss several traditional outings.
In fact, she was so poorly that Twitter even reported she had died, a rumour quickly shut down by Buckingham Palace.
However, she felt well enough on Thursday to give an award to a member of her household, the Daily Express reports.
Nevertheless, the 90-year-old monarch has passed on some of her duties to other members of the royal family and eyes are turning to the next-in-line for the throne.
For our look at the possibility of a King Charles, see here.
And after that? Charles is already 68; should he not prove as apparently immortal as his mother, Prince William will be next in line.
What does that mean for Kate?
William and Catherine "Kate" Middleton became the Duke and Duchess of Cambridge when they married. Were William to become king, Kate would probably be given the title of Her Majesty Queen Catherine, Royal Central says.
That title is purely a ceremonial one however, notes the International Business Times. As the spouse of a monarch, the role does not carry the full heft of the current Queen. She would only be a royal consort, as Prince Philip is today.
Also, if William died, Kate could not take over as ruler; the monarchy would pass to Prince George.
Which brings us to the monarchy's newest (and cutest) contenders…
Where are George and Charlotte in the line of succession?
They may be mere infants, but Prince George of Cambridge, aged three, and sister Princess Charlotte, who turns two in May, are third and fourth respectively in the royal succession, behind granddad Charles and their dad Prince William.
They're in front of uncle Prince Harry, who is followed in the line by Prince Andrew and his daughters, Princesses Beatrice and Eugenie, and then Prince Edward and his family, Viscount Severn and Lady Louise.
How likely is George to become king?
It's quite possible, but if his great-grandmother's longevity is anything to go by, George likely won't get a sniff of it for a very, very long time.
The Queen is the longest-reigning monarch alive today, with her rule at 64 years and counting. If Charles and William are next, "George could be well into his 60s before crowning," writes former BBC royal correspondent Christopher Lee in the New Statesman.
In a piece entitled Why Prince George Will Never Be King, Lee hypothesises the UK will get rid of the monarchy before either of William and Kate's children can rule.
Speaking to the BBC last year, William said he had not told his son he might be king one day. "We are a normal family," he said, adding that ruling is "not something that's at the top of my priority list to think about".
Hmm. What about Charlotte?
Charlotte is seen as the "spare" in the old "heir and a spare" mantra so unless George predeceases her, she won't take the throne.
Still, she was born after new changes were implemented to the royal line. The 2013 Succession to the Crown Act states that princes no longer take precedence over their sisters, removing the male-weighted primogeniture system which had been in place since 1701, the Daily Telegraph says.
Charlotte is, of course, younger than her brother so the rules don't apply. But the new law does mean that if William and Kate have another son, the Princess would remain fourth in line rather than being bumped down to below the newcomer.
The act is not retrospective, so anyone born before 2013 will not reap any benefits should there be a wipe-out at the sharp edge of the royal line.