The Queen celebrates Kate Middleton's 40th birthday with beautiful family photos

Happy birthday to the Duchess of Cambridge

kate middleton the queen prince william

The Queen has publicly marked the Duchess of Cambridge's milestone 40th birthday with a series of heartwarming photos posted to the royal family's official social media accounts.

The pictures shared on Twitter and Instagram showed Kate, who turned 40 on Sunday, smiling with the Queen during different events, including one at Trooping of the Colour in 2016. 

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The caption read: "Wishing The Duchess of Cambridge a very happy 40th birthday today!" 

WATCH: Kate Middleton's royal milestones as she celebrates her 40th birthday

It comes after the Duke and Duchess of Cambridge's household released official birthday photographs of the mother-of-three. In the portrait, Kate was pictured at Kew Gardens, wearing gowns by Alexander McQueen and jewellery loaned from the Queen. 

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While the royal family and royal watchers marked the day on social media, Kate is celebrating her milestone moment in private with her husband Prince William and their three children, Prince George, Princess Charlotte and Prince Louis. It's not known where Kate is spending her birthday weekend, but she may have chosen to ring in her fifth decade at the family's country home in Norfolk, Anmer Hall.

Given that the Duchess is incredibly close to her family, it's likely she'll have spent the weekend with her parents, Carole and Michael Middleton, as well as her siblings, James and Pippa, and their families. James is newly married to his French wife Alizee Thevenet, while Pippa shares two children, Arthur and Grace, with her husband James Matthews.

The Queen shared a lovely tribute to the Duchess of Cambridge on her 40th birthday 

In honour of her birthday, HELLO! spoke exclusively to those who know Kate best, from royal insiders and friends to charity representatives, who all revealed what the Duchess is really like behind closed doors.

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Of the Duchess' accomplishments in her ten years as a royal, one royal insider said: "I think she would say herself that she wasn't born to be a public figure. She's a reserved person and she's incredibly thoughtful, but she would never have sought a public role if it hadn't been for the man that she married."

© Photo: Getty Images

Kate has been part of the royal family for ten years

They added: "She's not a put yourself out there, extroverted type of person, it's just not who she is. But she knows it's an important way for her to make a positive contribution and there are some times that you need to get out there and speak for things you believe in.

"She works really hard to make sure the words are her words and really prepares. So when people hear her speaking it's genuinely what she believes. What you see is what you get."

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