Three portraits of the Duchess of Cambridge were shared to mark her 40th birthday on Sunday. Celebrated fashion photographer Paolo Roversi has revealed in an interview with Italian newspaper Corriere della Sera that Kate's husband and three children selected one of the pictures.

       Mr Roversi said William, George, Charlotte and Louis chose the black and white image of Kate smiling for the camera.

       Kate is wearing a white dress in the head and shoulder shot, which the photographer described as "where a carefree girl returns".

       In another one of the three snaps, which is also black and white, the future queen looks regal as she is shown in profile looking left.

       The Duchess's engagement ring is prominently on display and she is wearing Princess Diana's earrings.

       In the third photo, Kate looks glamorous in a striking red dress as she beams towards the camera.

       William's wife, who poses with her hands in her pockets, is wearing earrings loaned by the Queen.

       All of the gowns Kate wears are by Alexander McQueen and her brunette hair is loose and flowing in the trio of snaps.

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       Mr Roversi described photographing the Duchess as "a moment of pure joy".

       He said: "Taking the portrait of Her Royal Highness the Duchess of Cambridge was a true honour for me and a moment of pure joy.

       "I was moved by her warmth and friendly welcome and enchanted by her shining eyes that reflected the loveliness of her soul and her smile showing the generosity of her heart.

       "It was a profound and rich experience for me, an unforgettable moment. I have met a wonderful person, a person who, with her positive energy, can bring hope to the whole world."

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       The pictures will be shown in the community in Berkshire, St Andrews and Anglesey - all special places to Kate - as part of the National Portrait Gallery's "Coming Home" exhibition ahead of its reopening next year.

       The Duchess took to Twitter to share a rare personal message thanking well-wishers for her birthday messages, along with Mr Roversi and the National Portrait Gallery for the images.

       Kate wrote: "Thank you for all of your very kind birthday wishes. And to Paolo and the National Portrait Gallery for these three special portraits."

       She signed the tweet off with "C" for Catherine.

       The Duchess's milestone birthday heralds the start of an important decade for the monarchy and the future queen.