But while William and Kate have been busy meeting key workers and bonding with schoolchildren along the way, their three children Prince George, Princess Charlotte and Prince Louis have stayed behind at home at Kensington Palace. So who's looking after them?
Kensington Palace declined to comment, although it's expected the children are being looked after by their live-in nanny Maria Teresa Turrion Borrallo, who has worked for the family since George was eight months old.
WATCH: William and Kate surprise school children in Scotland
When she first started the royal job in 2014, Kensington Palace said in an official statement that William and Kate were "delighted" to have Maria on board.
An insider also told HELLO! that the Spanish nanny had "worked for other high-profile families and it was from there that the Cambridges heard of her and hired her." The insider added: "She is not married and doesn't have a boyfriend, as her life is totally dedicated to the family she is working with. She is known for being totally professional – married to the job."
Maria has worked for the Cambridges since 2014
Maria has been spotted on various occasions, whether it's walking the children in their local park in London or helping out on royal tours and royal weddings. But with three young charges to look after while the parents are away – George is seven, Charlotte is five and Louis is two – it's likely that Kate's mother Carole Middleton has also stepped in to lend an extra helping hand.
Carole, 65, is incredibly close to her grandchildren and has often been pictured arriving at Kensington Palace to look after the kids while William and Kate attend late-night engagements.
Carole Middleton may have driven down to London to look after her grandchildren
Under the current government guidelines, one household is allowed to link with one other household to form a childcare bubble, to "provide informal childcare to a child or children under 14". The Cambridges may well have done this with the Middletons, who live in Berkshire, and Carole may have driven down over the weekend before William and Kate departed on Sunday night.
If she is staying in Kensington Palace, there's no doubt she's been getting into the festive spirit with her grandchildren. In a festive Instagram post for her company Party Pieces, which she shared last week, Carole wrote: "Christmas Eve has always been a special occasion for my family."
William and Kate share three children
"Children get sweetly excited by the idea that Father Christmas is coming, and really want to give him something - and he'll really appreciate our new Christmas Eve sets and boxes. If you're planning a virtual Christmas, cousins in different households might enjoy organising their goodies for Santa together over a video call. Yours, Carole."
Make sure you never miss a ROYAL story! Sign up to our newsletter to get all of our celebrity, royal and lifestyle news delivered directly to your inbox.