With three of the four most senior royals out of action in the coming weeks, many gaps in their busy engagement schedules will need to be filled.
But a slimmed down monarchy has left the burden of duty with Queen Camilla, Prince Edward, Princess Anne and the Duchess of Edinburgh.
Many royal watchers will now be looking at the non-working Windsors to step up the mantle as Prince William stays by his wife Kate Middleton's side while she recovers from abdominal surgery and Charles undergoes an operation for an enlarged prostate.
While the obvious choice to fill these gaps maybe Eugenie and Beatrice, who are both Princesses and 9th and 11th in line to the thrones respectively, perhaps Zara and Mike Tindall are better placed to take on engagements.
The couple, who live together on Princess Anne's Gatecombe Estate in Gloucestershire, already have a closeness with the Wales family, are very popular with the public and have been hailed by experts as bringing 'a bit of normality' to the royal family. But could they become working royals?
Both professional sportspeople, their recent trip to Australia, for the Magic Millions competition, saw them receive a hugely positive reception internationally.
Despite being only 21st in line to the throne, and not having a title, Zara is the fourth most popular living royal, only behind William, Kate and Anne, while Beatrice and Eugenie rank 10th and 11th, according to YouGov.
Eugenie also spends most of her time in Portugal, while Beatrice split her time between the US and UK.
Zara and Mike however have their feet firmly on British soil, with school age children and a jobs in the UK.
Giles Kenningham, Founder of PR & Public Affairs Consultancy Trafalgar Strategy and former Number 10 Head of Press said that Zara and Mike are cementing themselves as the biggest earners in the royal family as Harry and Meghan have become 'tarnished'.
'Zara and Mike are sports stars in their own right so have more cachet than other members of the royal family,' he told Femail.
They have both earned millions from sponsorship deals while staying close to the royal family. But is it perhaps time they traded in their deals for a role in the Firm>
Yesterday, Buckingham Palace announced that King Charles will attend hospital next week to be treated for an enlarged prostate. It was also revealed that the Princess of Wales underwent surgery for an abdominal issue yesterday and will not return to public duty until Easter.
Who are the working royals?
His Majesty, King Charles III
Queen Camilla
The Prince and Princess of Wales
Anne, the Princess Royal
Duke and Duchess of Edinburgh, Prince Edward and Sophie
The Duke and Duchess of Gloucester, Prince Richard and Birgitte
Prince Edward of Kent
Princess Alexandra, the Honourable Lady Ogilvy
William is also expected to take on a lighter schedule as he concentrates on family life while the Princess of Wales recovers from two weeks in hospital.
It's likely Queen Camilla, Princess Anne, Prince Edward and the Duchess of Edinburgh could now take on any public engagements that both the King and the Princess of Wales are unable to honour.
Zara's mother Princess Anne is often lauded as one of the hardest working royals, and it's thought the couple could further warm to the public if they followed in her footsteps.
'They both have big followings, Mike with his podcast and Zara with her equestrian career so have more credibility than others,' Giles added.
'They're often pictured out with their children and seem more like a normal family than a royal one, making them relatable and marketable.
'Harry and Meghan have become somewhat tarnished which makes them the premier royal couple when it comes to deals'
Speaking on Channel 5's, Zara and Mike: No Nonsense Royals, last year, journalist Brenda Emmanus says that Zara and Mike are 'keen to do their own thing' and have sponsorship deals 'carefully crafted to support 'brand Tindall'.
'Mike Tindall has been an asset to the royal family in that he's a connection to normal people,' Brenda said.
'He has a great sense of humour and he's made them a very modern family.
'They live their own lives and make their own decisions, the public doesn't pay for them. They're practical and accessible, the most normal and delightful couple.
'They're keen to do their own thing and pay their own way. Sponsorship is carefully crafted to enhance brand Tindall, and they're making the most to be seen as the embodiment of country life,' she added.
The couple are also involved with charity work, a keen pillar for any working royal.
Mike has an annual charity fundraiser at The Belfry Golf Club in Sutton Coldfield which aims to raise money for Cure Parkinson's and the Matt Hampson Foundation.
William and Mike, 45, are known to have a close relationship, perhaps especially since Prince Harry and Meghan Markle's move to the US.
From casting off royal protocol to pull William in for a hug, to joking that he calls his wife's cousin 'One Pint Willy' because 'he is not the best of drinkers', it's clear Mike has cut through the royal stuffiness - and the heir to the throne loves it.
Speaking to The Telegraph, doyal biographer Ingrid Seward, editor in chief of Majesty magazine, said: 'Mike has that kind of sportsman camaraderie that would especially appeal to William, who was once a wild boy himself.'
She added: 'Mike gets funnier under the influence of alcohol and can be totally outrageous.
'William cannot do this anymore as he is too aware of his responsibilities. But he can live vicariously through Mike.'
Mike took on the role of 'fun Uncle', playfully slinging an arm around Prince George's neck as they made their way into church.
At the heart of William and Mike's friendship is William's bond with his cousin Zara.
He and Harry were raised in Gloucestershire, just a few miles from where Zara and her brother Peter Phillips grew up.
The four royal cousins were often spotted chatting and joking at royal events, with William previously revealing how it was 'hard to keep a straight face' when sitting opposite his cousins in church.
The bond between cousins is particularly close for members of the Royal Family, who might struggle to let outsiders into their inner circle.
Such is the closeness between the cousins that they are all part of a WhatsApp group where they exchange messages on upcoming events and family news.
'Me, my brother and then a few of Zara's side like her brother Pete [Phillips] and the cousins are on WhatsApp groups,' Mike once revealed. 'I wouldn't say we're cutting edge, but it's just easier for some reason on WhatsApp.'
He added on a separate occasion: 'It's just what you do to try and set up get-togethers and we are going to something that is the same.
'If you are going to go, [we discuss things like] "Are you going to take the kids?" Quite a lot of people have family WhatsApp groups.'
William and Mike have been photographed looking pally at several public engagements, with the ex-England rugby player going along to support the royal at polo matches in the past.
They have also been willing to get stuck in with the other's children. Mike has been snapped carrying Prince George, ten, on his shoulders, while William gave Mia, nine, a ride.
Zara and Mike also share Lena, five, and Lucas, two, while William and Kate are parents to Charlotte, seven, and Louis, four.
Inside Mike and Zara Tindall's £30M fortune: From her Rolex and Land Rover deals to his I'm A Celeb and cringe-worthy Domino's TV adverts
Mike and Zara Tindall have amassed an estimated £30million fortune from a number of shrewd deals, sponsorships and endorsements.
England Rugby legend Mike is the fourth richest former player in the UK with a net worth of £15million.
And his Royal wife Zara is no different, bringing in the same amount from her own business interests and work.
But some of the couple's money-spinners might surprise some, as Mike and Zara are involved with quite the variety of big names.
Here MailOnline takes a closer look at some of them:
Zara's Musto deal - £500,000
Throughout her life, Zara, 41, has been working closely with a number of brands, which have provided her with a solid portfolio.
She enjoys a long-standing relationship with sailing and outdoor brand Musto.
As an ambassador, she is featured on the firm's website saying: 'I started riding horses at a very young age and my mother was into sailing, which is how I became familiar with Musto as a sailing brand.
Musto then developed the equestrian and country range so it was natural to enjoy the brand's products for this area as well. The cut is flattering for women - you feel very feminine in them, while being functional. Jackets don't ride up or let cold air in and are made of premium fabrics that are strong enough to allow you to work and look good at the same time.'
It was previously estimated that King Charles' niece could have earned £500,000 for deals with Musto.
Mike's cannabis oil deal - £50,000
Mike, 44, has also been bringing money for partnerships of his own.
In 2019, Zara's husband announced a new partnership with Pueris CBD, a company selling cannabis products.
Its website proudly mentions the association, adding: 'Here at Pureis lots of our friends lead active lifestyles, with many who have spent their lives dedicated to sports.
'Like Sir AP McCoy OBE who was 20-time Champion Jockey, and Mike Tindall MBE rugby legend having 75 caps for England and played on England's winning world cup team in 2003.'
When he shared the new of his partnership on Twitter, Mike also offered his followers on social media a discount code.
It is estimated he will have received a £50,000 fee upfront as well as possible commissions from sales from his promotion.
Zara and Land Rover - £200,000
Zara has been collecting partnerships with legacy brands for years, one such relationship is Land Rover.
She became an official brand ambassador in 2006, strengthening the luxury 4x4 maker's already impeccable royal connections.
The Queen was thought to have had no fewer than 30 Land Rovers, while they are also driven by all of the Queen's children and most of her grandchildren - as well as the Princess of Wales' family.
Zara became the first person to be given the keys to a Range Rover Evoque in 2011 and has presented a women's scholarship for training in engineering, sponsored by the firm. And every year they sponsor her equestrian competitions.
It is estimated that Zara could be earning up to £200,000 a year from Land Rover.
