Sarah, Duchess of York joined the royal family for the Christmas Day church service for the first time this year in decades.
The author, 64, was seen walking alongside her ex-husband, the Duke of York, and their daughters, Princess Beatrice, 35, and Princess Eugenie, 33.
It is thought the last time Sarah was pictured walking to the church service with Queen Elizabeth II was in the early 1990s, which is normally reserved for close family.
Despite finalising their divorce in 1996, Sarah and Prince Andrew have remained good friends and still live together at Royal Lodge in Windsor.
Sarah shared a close relationship with her former mother-in-law, Queen Elizabeth II, and it is thought she has been a guest for Christmas lunch in recent years.
She has won plaudits in recent months for her battle with breast cancer, praised for speaking openly about her treatment and setting an example for other women to get screened.
Rachel Bylo, 85, travelled from St Albans and got the chance to wish Sarah a Merry Christmas told PA: "I suppose I’m a royalist and this was a good spot to see all of them.
"Sarah’s girls are her so it’s nice to have here with her girls – Eugenie and Beatrice are lovely."
For the walk to church, Sarah looked elegant in an emerald green Holland Cooper coat with matching leather boots and a velvet Gucci bag. She matched with her daughters by accessorising with a headband.
The Duchess also shared an older snap on Instagram, showing her linking arms with Beatrice and Eugenie in 2016, as she marked the festivities.
"We are enjoying each other’s company and feeling grateful today. I hope everyone has a wonderful day. Happy Christmas to anyone who celebrates and season’s greetings to all!" she captioned the post.
Sarah is grandmother to Beatrice's daughter, Sienna Mapelli Mozzi, and Eugenie's sons, August and Ernest Brookbank.
Ahead of Christmas Day, the Duchess revealed her plans with her grandchildren. Sharing an image of herself holding dolls of her characters from her Little Red children's book series, Sarah wrote: "We are wrapping plenty of toys (and books) to put under the tree! And it is about time to read Little Red's Christmas Story to my grandchildren again. How is everyone else spending this festive season?"
LISTEN: A Right Royal Podcast Christmas Special