A previously unseen portrait of the Prince and Princess of Wales has been released by Kensington Palace in celebration of the couple’s 13th wedding anniversary.

The photograph by Millie Pilkington – who took the most recent picture of the King and Queen to mark Charles’s return to public duties – shows William and Kate on their wedding day in 2011.

The black and white image was posted on the Waleses’ social media accounts on Monday and captioned “13 years ago today!”

It shows the newlyweds looking relaxed and smiling at Buckingham Palace after their ceremony, with Kate in her Sarah Burton for Alexander McQueen bridal gown and veil and William standing with his hand on his wife’s waist.

Kate, who is undergoing chemotherapy for an undisclosed cancer, married future king William after eight years of dating.

The couple are facing their most difficult challenge so far amid the princess’s diagnosis, with Kate appealing for time, space and privacy as she continues her treatment.

In an emotional message to the nation last month announcing her health news, she praised her husband for his support during “an incredibly tough couple of months for our entire family”.

“Having William by my side is a great source of comfort and reassurance,” she said.

Westminster Abbey, where the couple were married, shared archive footage of William and Kate emerging hand in hand from the church as husband and wife on their big day.

A message on the abbey social media account read: “Wishing The Prince and Princess of Wales a very happy wedding anniversary today!”

Last year, the Palace released a recent photo of the prince and princess to mark their wedding anniversary, showing them on bikes in the sunshine with their arms round one another.

But there was no new image of the couple this year as Kate continues her treatment for cancer away from the limelight.

Kate, 42, said in her video message how her diagnosis had come as a huge shock and that she and William “have been doing everything we can to process and manage this privately for the sake of our young family”.

The prince returned to work following the Easter holidays when the Waleses spent quality time with their three children Prince George, Princess Charlotte and Prince Louis.

Louis celebrated his sixth birthday last week and Charlotte turns nine on May 2.

William and Kate released an unedited new photo of Louis straight to social media to mark the youngster’s big day to thank well-wishers and avoid the uproar over the princess’s digitally altered Mother’s Day photo.

The prince is set to carry out engagements in the North East on Tuesday, visiting an Earthshot Prize finalist firm which makes low-carbon construction materials in Seaham, and opening James’s Place – a centre which offers free, life-saving treatment to suicidal men – in Newcastle.

Life partners for more than 20 years, William and Kate met at the University of St Andrews in Fife, Scotland, and became friends first before embarking on a romance.

William said in their engagement interview: “Obviously we both have a very fun time together, both have a very good sense of humour about things.”

The princess called him a “loving boyfriend” who was “very supportive of me through the good times and also through the bad times”.

They wed in a grand fairytale ceremony in Westminster Abbey on April 29 2011, with the aisle of the gothic church lined with trees.

The bride wore an intricate ivory gown with lace applique floral detail, while the groom was dressed in the red tunic of the Irish Guards.

William and Kate welcomed their first child George in 2013, followed by Charlotte in 2015 and Louis in 2018.

They have shared ups and downs, from the arrival of their children and the celebration of Jubilees to the late Queen’s death and more recently the King’s cancer diagnosis, and kept their counsel amid accusations levelled at them by the Duke and Duchess of Sussex in the wake of Harry and Meghan’s split from the royal family.

Buckingham Palace announced on Friday in a boost to the royal family that the King is to restart some public duties, with his medical team “very encouraged” by the progress he has made so far.

Thirteen is superstitiously considered an unlucky number but is also known as a baker’s dozen, which dates from medieval times when they would add an extra loaf to avoid being flogged for overcharging customers for their regulated goods.

Thirteenth wedding anniversaries are traditionally marked with the gift of lace.