Kate took a photo of the Duke, Prince George, Prince Louis and Princess Charlotte on a wooden swing in Anmer Hall, Norfolk. The photo was posted a day before William turned 38 years old, and was posted onto the Cambridge’s Kensington Royal Instagram account.
The photo was a hit with royal fans, and was the most liked picture from all Palace accounts last year.
More than 2.4 million Instagram users liked the candid family snap.
Other photos taken by Kate which made a splash on Instagram included a picture of the Duke playing with his children and portraits of Charlotte for her fifth birthday in May.
William rolling in the grass with the Cambridge kids racked up more than 1.4 million likes, while Charlotte’s portrait got over 1.7 million.
Speaking to ITV’s This Morning, Kate shared she had been practicing photography during the UK’s first coronavirus lockdown.
She said to hosts Holly Willoughby and Phillip Schofield: “Well I am very much an amateur photographer.
“I’ve sort of learned along the way but during this time I’ve spent lots of time picking up my camera and taking photographs of the children because they are always around us when we are doing stuff together, which has been great.”
In 2017, Kate was honoured by the Royal Photographic Society for pictures of Princess Charlotte as a baby.
Michael Pritchard, chief executive, said at the time the Duchess showed “talent and enthusiasm” behind a camera.
Last year, Kate launched her Hold Still photography project, where Brits sent in snaps of their coronavirus lockdown experience.
The Duchess was hands on with the project, commenting on submissions on social media and helped select 100 entries with a panel of judges.
A college of Hold Still photos was posted to the Kensington Royal Instagram, with a caption reading: “In May this year, in collaboration with the National Portrait Gallery, we invited people of all ages, from across the UK to submit a photographic portrait which they had taken during lockdown.
“The images present a unique record of our shared and individual experiences during this extraordinary period of history, conveying humour and grief, creativity and kindness, tragedy and hope.”
Queen Elizabeth II was shared some of the entries from the initiative by Kate, with the monarch praising the work.
In a letter, she said: “The Duchess of Cambridge and I were inspired to see how the photographs have captured the resilience of the British people at such a challenging time, whether that is through celebrating frontline workers, recognising community spirit or showing the efforts of individuals supporting those in need.”
Pictures from Hold Still even made their way into the Queen’s Christmas Day video message.
Some of the entries featured by the monarch included healthcare workers in PPE and a chapel with printed stand-ins of church-goers.