It's one of the most hotly anticipated events in the calendar for royal fans, bringing with it all the tradition, pomp and splendour so associated with the British Monarchy.
But it's also a chance for viewers and spectators packing The Mall to catch a glimpse of the very youngest members of the monarch's family.
Over the years I've been watching Trooping the Colour, the royal children have served up some of the funniest and most endearing images, reminding us that for all their status and privilege, kids will be kids, no matter how much you prepare them for their big moment in the spotlight.
See below for an explainer of what happens on the day, but the finale of the spectacle sees the royals gathering above the crowds in a moment of informality after the age-old ceremony.
Cue Prince Louis punching the air as military planes fly overhead, Savannah Phillips clamping her hand over Prince George's mouth and, going back a few decades, a young Prince Harry poking his tongue out at the crowds.
© Getty ImagesThe imagery all adds to the gaiety of the nation and offers some light relief from the more serious news topics of the day.
But it also serves to display the continuity the royal family represents and the sense of stability that brings with it.
© AFP via Getty ImagesSo in what has proved to be a very challenging year for the royals health-wise and amid the uncertainty of a General Election campaign, the presence of the young royals at events this Saturday will be crucial for The Firm.
''Everyone loves a bit of positive news,'' one royal insider tells me, ''And if the family can brighten up people's days, that's worth doing.''
© Getty ImagesPrincess Charlotte takes charge
But if you’re wondering who might be on hand to keep a lively Prince Louis in check on the day… ''don't worry, his sister will do that,'' jokes someone close to the royal fold.
Princess Charlotte has often been seen keeping her older and younger brothers in order at major public events, as I wrote about here.
These public moments for the Wales children, who otherwise enjoy a relatively private life, thanks to the fierce protection of their parents, give us a glimpse into their personalities and a sense of the fun they must have behind closed doors.
© Samir Hussein/WireImagePractice makes perfect for Prince George
With the King's own health concerns ongoing and as he and the Queen continue to work long beyond the age when most people retire, it's vital for the young royals to be seen and for the public to build a connection with them.
Prince George is still seven years off adulthood, but it’s vital for him to maintain his bond with the people he will eventually serve.
In the same way, so many people I speak to say they feel an affinity with Prince William because they have watched him grow up and now feel they know him.
© Tim Graham Photo Library via GetFor George, Trooping the Colour will also likely be an important part of his diary as the future Commander-in-Chief of the Armed Forces, so it all adds to his own understanding and experience of military and ceremonial events.
One of the most striking memories I have of the royals lining up on the Palace balcony is that of Prince George beaming up at Queen Elizabeth II at the end of celebrations to mark her Platinum Jubilee in 2022.
I got a sense of how much he admired her and was learning from her, despite the nearly eight decades between them. It was to be her last-ever balcony appearance and came three days after her final Birthday Parade.
© UK Press via Getty ImagesWho should appear on the balcony?
Of course, one of the hottest debates around Trooping the Colour is who should appear on the balcony.
The family lines up each year to watch the 1pm flypast of military aircraft, which ends with a spectacular display by the Red Arrows, trailing their patriotic red, white and blue smoke overhead.
But over the years, that line up has been edited down and currently only senior working royals are invited out to wave to the crowds.
It’s a change that has happened partly by accident and partly by design.
© Getty ImagesBefore his accession to the throne in September 2022, we regularly heard how the future King Charles was keen to present a '''slimmed-down'' monarchy during his reign, conscious of historic criticisms levelled at minor royals who were sometimes accused of being ''hangers on''.
Until the final years of his late mother’s reign, the balcony regularly heaved with cousins, nieces, nephews and their own families, sometimes raising eyebrows over how much all these family members might be costing the public purse.
But ahead of 2022's Trooping the Colour, which followed a two-year hiatus because of the Covid-19 pandemic, the Palace said: ''After careful consideration, the Queen has decided that this year's traditional Trooping the Colour balcony appearance on Thursday 2nd of June will be limited to Her Majesty and those members of the Royal Family who are currently undertaking official public duties on behalf of the Queen.''
Trooping the Colour
© Samir Hussein/WireImageWhat is it?
Trooping the Colour is a military ceremony performed by regiments of the British Army to celebrate the official birthday of the British sovereign. While Charles' actual birthday is 14 November, official celebrations always take place in June.
When is it held?
In 2025, it is scheduled for Saturday 14 June.
Where is it held?
Central London, with the procession route travelling from Buckingham Palace to Horse Guards Parade, along The Mall, and back again.
Who attends?
- King Charles III (in recent years, he has participated on horseback).
- Household Division: including the Foot Guards and Household Cavalry.
- Senior royals, such as the Princess Royal and the Prince of Wales often ride on horseback or appear on the palace balcony - like the Princess of Wales
Why is it called Trooping the Colour?
One regiment's colours (flag) are "trooped" (carried) before the monarch. The event ends with an RAF flypast over Buckingham Palace, viewed by the royal gamily from the balcony.
Historical roots:
It dates back to the 17th century and became an annual event to mark the sovereign’s official birthday under King George III in the 18th century.
Official celebrations to mark the sovereigns' birthday have often been held on a day other than their actual birthday, particularly when the day has not fallen on a day in the summer.
Where can I watch it?
The ceremony is broadcast live by the BBC and covered globally.
That year, in what was to be her final appearance at an official birthday parade, Queen Elizabeth II was one of just 18 to appear on the balcony, including Princess Alexandra, Lady Louise and James, Viscount Severn.
The change in approach neatly served to explain the absence of Prince Andrew, who had stepped back from public life in 2019, in the wake of his controversial Newsnight interview about his relationship with Jeffrey Epstein.
It also explained away the absence of the Duke and Duchess of Sussex, who were no longer officially on the payroll after leaving to start a new life in the United States.
© WireImageThe King's slimmed-down monarchy
But last year just 14 members of the King’s family emerged from the famous doors of the Palace's Centre Room.
And this year that number may fall further still, given Kate has been continuing her recovery in private.
As another seasoned royal watcher observed: ''Looking back on the old photos, it seems a shame to only include the Wales children these days.''
So should King Charles relax his stance and invite more of the younger family members to boost numbers?
© WireImageI know royal watchers would love to see more of the Wales children interacting with their cousins Savannah and Isla Phillips and Mia, Lena and Lucas Tindall.
But if he did allow numbers to swell, he would need to extend an invitation to other non-working royals, which given the ongoing tensions between Princes William and Harry and the difficult question of Prince Andrew’s status, could cause problems.
A quick explainer: What is Trooping the Colour?
Trooping the Colour dates back to the Middle Ages, when each Lord or Baron flew his banner, or ''Colour'' to allow followers to distinguish him in battle
The Colour also served as a rallying point for troops amid the chaos of war, so to help them recognise it, they practised parading with an officer carrying the Colour along the ranks.
The tradition of carrying a Colour on the battlefield ended in the late 19th Century, but the ritual has continued in ceremonial form to this day, with Trooping the Colour marking the British Sovereign’s official birthday for more than 260 years.
© Getty ImagesThe annual event gives the Household Division a chance to demonstrate their professional excellence and loyalty to the Crown and the honour rotates between the five regiments of Foot Guards.
This year it falls to Number 9 Company Irish Guards, who will be led by their regimental mascot, an Irish Wolfhound named Turlough Mor, who is affectionately known as Seamus.
During a dazzling military ceremony on Horse Guards Parade, watched on by the royal family and thousands of spectators, as well as millions of TV viewers worldwide, they will troop a new Colour, presented to them by the King just this week.
