Prince Andrew and Sarah Ferguson have been separated since 1996, but the couple have remained close to raise their two daughters, Princess Beatrice and Princess Eugenie.
Sarah, who once described them as "the happiest divorced couple in the world", continues to play a role in the Royal Family and supports Andrew at major events.
Though the Duchess of York was not invited to the Coronation service at Westminster Abbey, she did get a seat in the Royal box next to her ex-husband last night.
The pair were seen putting on a friendly display to celebrate the second day of celebrations, sat near their glamorous daughters as well as the King and Queen.
Fergie, 63, said she wasn't offended by Charles' snub because she and Andrew were divorced and "you can't have it both ways".
The Duchess, who took on the late Queen's two corgis after she passed, celebrated with the dogs at home - in her and Andrew's Windsor-based residence, Royal Lodge.
She previously told ITV's Good Morning Britain: "I am divorced, and I'm really loving being divorced to my ex-husband, not from my ex-husband, it's quite a differentiate."
A friend of Fergie's told the Daily Mail that she "has been hugely supportive of Charles and Camilla and does not want this to become about her".
Sarah marked the moment on Instagram and congratulated the newly-crowned King and Queen by sharing a sweet snap of them leaving Westminster Abbey.
She captioned the social media post: "Sincerest congratulations to Their Majesties, the King and Queen."
It was a star-studded evening at Windsor Castle last night with the Royal Family enjoying the celebratory gig, with the likes of Katy Perry, Take That and Lionel Richie taking to the stage.
Beatrice and Eugenie appeared excited to attend the event, joined by their husbands Edoardo Mapelli Mozzi and Jack Brooksbank, sat behind the Wales family.
Earlier this year, Sarah spoke exclusively to the Mirror about Andrew 'fully supporting' her next major career move, to turn her novels into television dramas.
"I'm going to let you into a secret," she explained before adding: "We have been talking to production companies and there is real interest in turning both novels into a period TV drama.
"I am so excited about it, I would love to see someone like Jess Buckley play my heroine."
Despite the gruelling schedule, the Duchess says her daughters are "hugely supportive", while Andrew "tells me they [books] are fabulous".
In a move which would please the King, she explained: "One thing I would like to do is front a documentary about the challenges facing the environment.
"I feel very strongly that my generation bears a heavy responsibility to address issues like climate change and plastic in the oceans so that our children and grandchildren inherit a sustainable planet."
Sarah also reflected on the loss of the monarch and said they are all missing Queen Elizabeth "enormously".
"Her passing has left a real void in the family, as she herself said, grief is the price we pay for love," she said.
