Princess Eugenie was one member of the royal family who didn't appear at the Princess of Wales's comeback carol service last night, which was attended by swathes of royals.
Kate Middleton, 42, hosted the 'Together At Christmas' carol service - which will be aired on ITV on Christmas Eve - at Westminster Abbey as she slowly returns to public life after a difficult year.
The Princess of Wales underwent major abdominal surgery in hospital at the start of the year, after which doctors broke the news that they had found evidence of cancer and advised her to undergo a gruelling course of preventative chemotherapy.
She took a step back from public life while undergoing chemotherapy, and has in the latter half of the year started to appear again at a number of royal gatherings.
Last night, Kate was joined by her husband Prince William and their three children - Louis, six, Charlotte, nine, and 11-year-old Prince George.
Other members of the royal family also attended, including Princess Beatrice with her husband Edoardo Mapelli Mozzi and her stepson Christopher Woolf.
However, her sister Princess Eugenie was not in attendance.
The details around her absence are unclear, but it likely because of her decision to split her time between the UK and Portugal with her husband and two sons, August and Ernest.
Princess Eugenie was one member of the royal family who didn't appear at the Princess of Wales's comeback carol service last night, which was attended by swathes of royals
It is understood that her husband, Jack Brooksbank, works in Portugal with Michael Meldman's Discovery Land Company.
However, she wasn't alone in skipping the event, with the King and Queen also absent.
A royal source told the Express: 'The villa in Portugal is more an investment than anything else and construction hasn't even been completed yet.'
They added, 'It hasn't been purchased as a new home, but more as a holiday retreat and something they can put their money into to protect their assets.'
Earlier this year, Princess Eugenie gave rare insight into her life in Portugal - and her children's favourite pastime there.
The 34-year-old royal revealed that her sons - August, three, and Ernest, one, 'love swimming', despite her being 'scared' of the ocean growing up.
Other members of the royal family also attended, including Princess Beatrice with her husband Edoardo Mapelli Mozzi and her stepson Christopher Woolf
The details around Eugenie's absence are unclear, but it likely because of her decision to split her time between the UK and Portugal with her husband and two sons, August and Ernest
Princess Beatrice, who is expecting her second child, attending the service last night
She added: 'The sea in Portugal's a little bit rougher. So, we've got out feet in, but Augie is a fish. He literally loves it, and we have whales and dolphins across the walls.'
Eugenie, who is married to Jack Brooksbank, 38, added in conversation with Hello!: 'We've got a book called The World's Wildest Waters, which is backed by Blue Marine Foundation - I see it every morning when Augie's eating breakfast, and he's like, ''Mama!'' and then we go through it.
'The children have to find the creatures in the pictures and the next page is all the facts about the cuttlefish, or the Great White shark or the seal. And Augie loves it.'
Eugenie spoke to the magazine during a visit to Christie's to see Blue: Art, with pieces set to be auctioned off to raise funds for Blue Marine Foundation.
Kate was full of laughter as she chatted to some of her guests at the carol concert, including Paloma Faith
The princess (pictured) has been ‘hands on’ over every aspect of the service and held regular planning meetings at Windsor
The Princess of Wales sat net to Prince Louis and Princess Charlotte, who matched their mother's red ensemble, during the carol concert
Prince Louis and the Princess of Wales during the Together At Christmas carol service
Unlike her children, the eco-conscious royal previously revealed how she was once terrified of the ocean, despite now championing efforts to reverse environmental damage to it.
In June, the Princess took to Instagram to share an adorable childhood photograph of herself at the seaside ahead of World Ocean Day.
The then-young royal grinned towards the camera in the image donning a blue swimsuit and matching bucket hat with a generous layer of sun cream on her face.
Since becoming a mother to her children August and Ernest, the daughter of the Duke and Duchess of York has taken up environmentalism in the hope of helping future generations.