A ROYAL expert has told how Prince William's birthday tribute to Kate is his most moving yet.
Hugo Vickers unpacked the intimate message, saying it signals a new era after the couple's toughest year to date.
Wills, 42, marked Kate's special day with an unprecedented personal post hailing her unwavering "strength" on Thursday.
In the heartfelt tribute on X, published on January 9, Prince William shared a message to his beloved wife and the mother of his three children George, Charlotte and Louis.
The post read: "To the most incredible wife and mother.
"The strength you've shown over the last year has been remarkable.
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"George, Charlotte, Louis and I are so proud of you.
"Happy Birthday, Catherine. We love you. W."
The tender tribute has racked up millions of views on the platform with hundreds wishing the Princess a happy birthday.
With the post, Will released an unseen picture of Kate where she appears glowing, looking relaxed in jeans and a gingham scarf.
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The glorious snap was taken by photographer Matt Porteous who took the portrait in Windsor last summer.
Users on X were quick to compliment the stunning picture, and support Kate alongside the Prince's birthday wishes.
Huge Vickers told the Sun William's sweet tribute could signal a new openness from the royal family since his wife's cancer diagnosis.
Kate was diagnosed with cancer early last year which led to a lot of speculation from the public.
The Princess moved away from the spotlight during this time but has since has pledged a gradual return to Royal duties.
Hugo said: "William mentioned the word strength, and I think that is one of her quiet qualities.
"It's sort of an inner strength that she has a confidence and something which is not in any way overt or explicit.
"But it's just there, and I think that's one of the things that we admire about her, her resilience and her determination."
The post follows a punishing year for the family, with Prince William describing 2024 as the "hardest year in his life."
It came with Prince Charles' cancer diagnosis, and Princess Catherine's shock cancer announcement.
The year was branded as “annus horribilis” - one of the worst years the Royals have faced.
Hugo says the Prince's loving message to his wife is particularly significant this year because of how difficult the last year was.
He added: "I've got sympathy for Prince William, because he must have had a pretty difficult year himself, and he has indeed said so, and in fact, he said, it was the most difficult year of his life.
"Having a wife who is not well, and three small children, and all the other responsibilities that come with his position in life, he's got a lot on his shoulders, and I think he's handled it very well."
Hugo explained the tribute demonstrates solidarity in marriage, teamwork, and the importance of family and unity.
Prince William mentioned strength and Hugo believes the post itself emphasises how the couple are strong together.
"We all admire her hugely, and I personally think she's the great star of the Royal Family, and she's the great hope of the future," he added.
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"One day she'll make a wonderful queen."
Princes Kate celebrated her birthday surrounded by family and said she is preparing for a "gradual return" to royal duties.
MATT WILKINSON Wills’ break with tradition to share public declaration of love for Kate puts end to Royal Family’s ‘stuffy’ stereotype
By Matt Wilkinson, Royal Editor
PRINCE William’s public decoration of ‘love’ for Princess of Wales on social media on her birthday is pure #couplegoals, as they say online.
Anyone who persists in the myth the Royal Family are stuffy and unable to show emotion needs to take a rain check today.
Prince William is not only seen as a popular and modern face of the royals in the 21st century but now showing he is relaxed about confident about telling everyone exactly how he really feels about Kate.
Sure we all watched as he declared his love and devotion for Kate in Westminster Abbey back in 2011 - but that was their wedding!
His genuine heartfelt birthday message to millions on social media today hailing his ‘incredible’ wife while also celebrating her ‘strength’ as ‘remarkable’ during a year where she has faced cancer is a welcome public gesture in hard times.
Writing also of George, Charlotte and Louis, declares on social media ‘We love you’. Have we ever seen this kind of display attention from a royal before? No chance.
It is #couplegoals, as they say on social media.
This openness is a direction the couple have been moving for many years. It comes as no surprise as those of us who have witnessed the couple together in recent years can testify.
There is often a shared smile, a nod, a gentle arm around the waist, or even a holding of hands.
But this birthday message is also a clear sign, coming after he admitted that 2024 had been one of the hardest of his life, that William is happy to tell the world how he feels when the time is right.
This personally written message signed ‘W’ is a welcome change from a palace office worker posting agreeable birthday message with some archive photos which we normally see on each occasion.
It’s January, it’s dark and cold outside, we are all skint and overweight after festive indulgence, so let’s enjoy and revel in a little slice of love and happiness.
But it’s Kate’s big day and there will be so more messages from around the world wishing the princess many happy returns as she turns 43-years-old - including everyone here at The Sun.
And while over the last 12 months there has been a lot of nonsense posted on social media about the Princess of Wales - this year let’s try and only remember this special one.