• Kate Middleton released three portraits Sunday to celebrate her 40th birthday
  • Prince William and their kids picked the close-up shot of the duchess smiling in a one-shoulder dress
  • Photographer Paolo Roversi said some photos from the shoot have yet to be released, including one of Middleton dancing

Kate Middleton released three portraits Sunday to celebrate her 40th birthday, and one of them was chosen by her husband Prince William and their children.

In an interview with Italian newspaper Corriere Della Sera, Paolo Roversi, the photographer who captured the Duchess of Cambridge's portraits, opened up about his experience working with Middleton during their November 2021 photoshoot at London's Kew Gardens.

The photographer revealed that Prince William and the couple's three children — Prince George, 8, Princess Charlotte, 6, and Prince Louis, 3 — helped pick one of the photos that would be released on Middleton's birthday.

Middleton's husband and kids chose a close-up shot of the duchess smiling in a one-shoulder dress with her hair swept over her shoulders.

It's "where a carefree girl returns," the photographer said of this snap, as quoted by People.

Roversi said that the three portraits showed "different" sides of the duchess. The black-and-white image where she sits in a traditional side profile pose seen in many royal portraits over the years "is regal and has a maturity that goes beyond her age, and the white dress dampens the seriousness of an effigy."

Middleton's photo in a red one-shoulder gown, on the other hand, showed her more "glamorous" side.

To keep the photos "contemporary," the photographer said he used only natural light, little makeup and no hairstyle

Roversi added that there were photos from the shoot that have not been released, and one of them features Middleton dancing.

"In the end I wanted to take pictures in motion, so with that wonderful wide skirt I made her dance in front of my camera, a kind of accelerated waltz mixed with a pinch of rock 'n roll," he shared.

Middleton's birthday portraits received mixed reactions on social media upon their release, with some claiming they were "too old-fashioned," while others thought they were "iconic."

"Not good. Makes her look about 60. It's far too old-fashioned. Honestly how many 40-year-olds would dress like that for a shoot. No atmosphere. Typical house of Windsor," one person commented.

"I'm speechless, this image is simply iconic and will go down in history! I really don't know how to react, I'm just mesmerized by the beauty, elegance and perfection of this portrait of the Duchess of Cambridge," one supporter wrote.

The portraits will enter the permanent collection of the National Portrait Gallery, of which Middleton is patron.

Middleton's photos will be displayed over the course of the year in three places that hold special meaning to her: Berkshire, St. Andrews and Anglesey.

The duchess grew up in Bucklebury, Berkshire, while she met Prince William at the University of St. Andrews in 2002. Anglesey is where the couple lived after their royal wedding in 2011.

Kate Middleton and Prince William
EDINBURGH, SCOTLAND - MAY 27: Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge attend a Beating of the Retreat at the Palace of Holyroodhouse on May 27, 2021 in Edinburgh, Scotland. Jane Barlow-WPA Pool/Getty Images