SARAH VINE: What troupers! This was a Royal Family pulling together through thick and thin – and courageous Kate was the dazzling cherry on the birthday cake

There are troopers and there are troupers. Today was a party for both.

Trooping the Color in honor of King Charles’ official birthday (he is two in King Years) was a dazzling, heady reminder of the skill, discipline and loyalty of our armed forces.

But not even Seamus the Irish Wolfhound or Apollo and Juno, the two beautiful drumming horses, could compete with the most dazzling trouper of them all: the Princess of Wales, in her first public appearance since announcing she was undergoing treatment for cancer.

As her carriage pulled out of Buckingham Palace, the crowd – dodging giant raindrops and a robust police presence along The Mall – craned their necks to catch a glimpse.

The King and Queen led the way in their glass-topped charabanc – Camilla chic in a cream ensemble; Charles looks very good indeed, despite his own health problems.

But as they circled the gleaming gold statue of Queen Victoria, the photographers’ lenses were all trained on the slender figure in the carriage behind.

Striking in a white dress with black trim and matching hat (almost identical to the one worn by Audrey Hepburn in My Fair Lady, a fact quickly spotted by eagle-eyed viewers on social media), her hair in her signature low chignon, the princess van Wales was accompanied by her three children, George, Charlotte and Louis.

It’s not the first time that Charlotte’s outfit mirrored her mother’s – a sweet touch. If the children were affected by the princess’ illness, it was not evident from their behavior. Charlotte was as sunny as ever (and still very much the spit of her late great-grandmother); George was his usual solemn self; and the sociable Louis – who always puts on a show – was full of mischief.

There were plenty of smiles and waves as they drove through The Mall, much to the delight of the crowd. According to a lip reader, George said to his mother, “They all look so happy.”

Such occasions are well rehearsed in the calendar of royal events. But there was something extra special about today.

It wasn’t just the unexpected and welcome presence of the princess, who only announced last night that she planned to take part in the pageant, after previously saying she would not be able to attend.

It was also the added symbolism of a royal family uniting through thick and thin, in sickness and in health, despite some very difficult years.

At a time of global unrest, and especially as the country prepares for a major change in government, people see the monarchy as a stabilizing influence.

Recent setbacks have threatened that stability: first the death of Queen Elizabeth II, then the King and Princess of Wales being diagnosed with cancer within weeks of each other – all against the backdrop of the acrimonious departure of the Duke and Duchess of Sussex, and Andrew’s continued misery.

The Princess of Wales waves from her carriage next to her three children, including the mischievous Prince Louis

Eagle-eyed viewers said the princess’s dress was almost identical to the one worn by Audrey Hepburn in My Fair Lady

But although all that weighed heavily on the Royal’s thoughts, it was not clear today.

This was more than just a show of unity; it was a show of strength, discipline and determination to persevere despite setbacks as impressive as those on the parade ground.

All the major players in King Charles’ new, downsized monarchy were present, present and correct: the Princess Royal, playfully piloting her troublesome horse; the Kents, the Edinburghs (with Sophie looking stunning in yellow).

Kate’s presence was the icing on the birthday cake.

It’s hard enough to muster the willpower to perform even basic actions while undergoing chemotherapy, as countless cancer patients know. There are days when even getting dressed can seem like an insurmountable challenge. The idea of ​​being finished to perfection and putting it on public display for the cameras of the world would be enough to make any ordinary person hide under the duvet.

But not the Princess of Wales. In her statement yesterday, she said she has good days and bad days; today was clearly a good day, or if it was a bad day you would never have known.

The procession, led by drum horses Apollo and Juno, parades through The Mall

Seamus the Irish Wolfhound was one of the stars of the day

There was no denying that she looked a little weak, and there were times when she seemed quite preoccupied. But she was fully present to keep an eye on Louis, whose irrepressible personality has its challenges, especially in such formal situations.

Besides his usual facial features (he really has quite a wide repertoire of expressions), at one point he was seen playing a blind jerk and asking his mother, “Do you know how they make these things, Mom?”

But apart from the meddling fingers, it all went smoothly. Even the weather waited until the main participants were safely back in their horse-drawn carriages to let loose in wonderfully British fashion.

And then, at just the right moment, the sun shone for that all-important balcony moment, as the princess and the king stood shoulder to shoulder side by side in their battle.

Last year it was William next to his father; this was an open gesture of support on behalf of the king. And that is understandable. They have so much in common, these two. Not only in terms of the health challenges they face, but also in the way their reputations have been tarnished by the same two people thousands of miles away in Montecito.

Rather than breaking them, as may have been intended, the experience seems to have only strengthened their resolve, making them both even more determined to fulfill their duty to the British people – and to each other. It is a show of moral courage that is rarely seen these days.

It also reminds us that words are all very well and good, but it is the actions that count.

A sunny Princess Charlotte and her brother Prince George smile at the spectators from their carriage

When Meghan married into the royal family, there was a feeling that she would have the same glamorous, fabulous appeal as a young Princess Diana.

She talked well and certainly looked good. Kate seemed rather sedate in comparison.

But when the going got tough – as life inevitably does from time to time – the Duke and Duchess of Sussex jumped ship and did their best to sink the ship. But the British royal family is, it seems, unsinkable.

Faced with a different set of challenges, which are arguably much tougher, the Princess of Wales has shown that she is made of much tougher stuff. Not only does she have resilience, she also understands the value of discretion.

Unlike Meghan, she commands respect not because she demands or expects it, but because she has earned it.

For the folks in Montecito, this might be like a Riviera Orchard marmalade dropper; but that’s the difference between just being a pushy princess – and a future queen.