The Duke of Cambridge turned 40 this week, and the extent to which the Queen has singled out her grandson has the potential to really ruffle some royal feathers.
What do you give a future King for a birthday present? A small island off Nova Scotia? A Faberge egg to go beside his Xbox? A half-share in his beloved Aston Villa football team?
Her Majesty could probably spare one of her Faberge pieces or find a spare bit of the Commonwealth to palm off on her grandson, instead she has gone an even thriftier route.
There was her fun pressie, the one that will necessitate a small army of footmen trooping down to the cellars and bringing up case after case of Bollinger and Pol Roger, the Queen's favourite sparkling tipples.
The Mirror reported that the 96-year-old offered to host a combined birthday shindig for both William and his wife Kate, Duchess of Cambridge (who turned 40 in January) at either Windsor Castle or Sandringham in the coming months.
The royal kitchens are probably already getting a head start on the battalion of cocktail quiches and venison sausage rolls they will need for the Turnip Toff crowd.
Then came William's actual birthday on Tuesday when Buckingham Palace marked the big day by throwing up some social media congratulations. However, what set this year's post apart was the palace's clear change of tack, sharing a Twitter thread which was a pretty blunt marketing exercise of William as a king-in-waiting.
Even for a man who will one day sit on the throne, these two Palace moves represent a dialling up of William's golden boy treatment. And therein lies the rub.
First, there's the party. While Her Majesty, only a handful of years shy of her century, might be a bit past knocking back the bubbles until midnight and enjoying a spin around the dance floor to Bobby Daran, over the years she has proven to be an enthusiastic host.
In 1990 she held the famous Dance of the Decades at Windsor Castle, thrown to mark the Queen Mother turning 90, Princess Margaret turning 60, Princess Anne turning 40 and Prince Andrew 30.
(Best not mention that in 2006, Windsor Castle was the setting for Princess Beatrice's 18th birthday celebration, with Jeffrey Epstein, Ghislaine Maxwell and Harvey Weinstein all on the guest list.)
William and his cousins Zara Tindall and Peter Phillip were all recipients of 21st birthday bashes at Windsor.
However, in singling out William and Kate with this right royal knees-up, the Queen stands liable to potentially put a number of noses out of joint.
As far as has been reported, she has not extended similar offers to her other grandchildren who have already hit their 40s.
What seems clear is that Her Majesty's generosity here reflects the high esteem with which she clearly holds the Cambridges. They have been Very Good HRHs in the past few years, proving to not only be diligent monarchical foot soldiers but having a clear vision of what it will take to keep the royal house going in the decades to come.
That includes big projects which engage with the most pressing issues, such as climate change and mental health, rather than piecemeal charity visits that involve wooden speeches and a spot of handshaking.
William and Kate have smiled, procreated and by and large steered clear of creating any scandals of their own. This fete looks very much like a reward for all of that good work; the gold star to end all gold stars.
But how will this boon play in other royal quarters?
William and Kate's destiny, to end up on thrones, stamps and limited edition coins, is very obviously a world apart from that of their cousins, the majority of whom have jobs, mortgages and don't have to clear time in the schedule for portrait sittings.
Inequity – the fact that some Windsor progeny receive vastly different treatment from others – is baked into royal life, but that does not mean that seeing it writ large might not grate or ruffle feathers.
The Queen has six other adult grandchildren aside from William, how must they feel seeing her party largesse extending only so far?
Then there's Buckingham Palace's William Twitter posts, postmodern idolatry at its finest.
Social media birthday wishes from all the royal households – Buckingham Palace, Prince Charles and Camllla, Duchess of Cornwall's Clarence House and the Cambridges' Kensington Palace outfit – usually follow a stock standard format.
Shots of the birthday boy or girl and one or two images showing them with that household's principal/s. The palace has generally stuck to this formula.
In 2021, for his 39th birthday, we got served a series of images setting up William the soldier, William the dad, and William the pre-eminent do-gooder.
In 2020, the Palace shared one image of the Queen and William smiling together.
In 2019, we got a shonky collage of images of the Prince, several of which showed him with the "Top Lady".
Had someone just taught a corgi how to use Adobe?
You get the drift.
But this year? A lengthy Twitter thread which, after the usual well wishes, read "As the second in line to the throne turns 40, learn more about His Royal Highness" and then went on to cover his key achievements such as being born, getting a middling geography degree, graduating from Sandhurst and becoming an air ambulance pilot.
The whole thing finished with a flourish, plugging his current royal gig – trying to change the world in between deftly wielding a sword for investitures.
The whole thing was part CV, part LinkedIn profile and all social media love-in.
Translation: This was Buckingham Palace shifting into hype man mode, a transparently more forceful attempt than we have seen before on his birthdays to really drive home the message that William is a future sovereign.
Someone has clearly been reading all about brand strategy.
Again, this move carries with it the risk of upsetting the various competing egos that make up the royal family.
Charles and Camilla are in Rwanda this week for the Commonwealth Heads of Government Meeting (Chogm), the first royal visit ever to the formerly war torn nation. On Wednesday, the couple visited Kigali Genocide Memorial and then Nyamata Church, where 10,000 Tutsis were murdered in just two days.
The Prince of Wales' sensitivity to his son's popularity eclipsing his own and William's royal work outshining his own has been widely reported. Too much of a focus on just what a smashing King William will be and too much bigging up of his future reign carries with it the potential to upset the delicate balance of princely egos.
When Charles hit this particular milestone birthday, his young sons gave him a badge that read "Life begins at 40". Here's hoping for the best is yet to come for William and Kate – the monarchy just might depend on it.
• Daniela Elser is a royal expert and a writer with more than 15 years' experience working with a number of Australia's leading media titles.