The reason why Princess Kate did not accompany Prince William to tiara event at the palace

The Princess of Wales is usually a regular fixture at the annual diplomatic reception, but on Tuesday her husband, the Prince of Wales, put in a solo appearance at the white-tie event at Buckingham Palace.

Kate, 42, has only missed the reception once since she made her debut in 2013 – and this was in 2014 when it clashed with her and William’s visit to New York.

Over the years, the Princess has wowed in an array of glittering gowns and tiaras, last year wearing a shimmering pink Jenny Packham dress with the Lover’s Knot tiara.

But it’s been a difficult year for the Waleses amid Kate’s cancer diagnosis and she’s making a gradual return to her public duties after completing chemotherapy in September.

For now, the Princess is concentrating on her upcoming Christmas carol service at Westminster Abbey on 6 December, with the service reflecting on “how much we need each other, especially in the most difficult times of our lives”.

“Kate’s very aware of what the future holds so she’s taking the time to focus on getting fit and strong again while she can and doing it on her terms,” royal biographer Robert Jobson told HELLO! in the latest issue of the magazine.

Meanwhile, royal author Robert Hardman added: “There will be a gradual scaling up of her activities in the new year, perhaps with some office-based engagements relating to her early years work.

“The Palace will be keen to manage expectations. If she did start returning to major social events, that would lead people to think things are back to normal, which isn’t the case. So I think there’s no pressure on her to do that.”

While Kate will play host at her Christmas concert, it is yet to be confirmed whether she will be involved in the state visit to the UK by the Emir of Qatar from 3 to 4 December.

Kate wore the Lover’s Knot tiara for the first time at the diplomatic reception in 2015, teamed with an ice blue lace gown and Queen Elizabeth II’s diamond chandelier earrings.

The pearl and diamond headpiece is synonymous with the royal’s late mother-in-law, Diana, Princess of Wales.