Sarah Ferguson has taken to Twitter to share an emotional plea with her followers.
The 63-year-old – married to Prince Andrew from 1986 to 1996 – posted a link to a Just Giving page set up for her friend who suffers with MND (motor neurone disease).
Earlier this month, John Chart, along with a great Pilgrim Bandits team, reached Everest basecamp and performed two skydives from a helicopter at 23,000ft in front of Mount Everest. He is now travelling from basecamp on to Camp 1.
Sarah told her followers: "This is my friend John Chart's last trek. John, who suffers from #MotorNeuroneDisease, climbs Everest to raise awareness about MND and how more research is needed. Support John by donating to help find a cure & share."
You can find out more about John’s story here.
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On Sunday, Sarah was spotted in a car with Prince Andrew leaving their home, Royal Lodge in Windsor.
She was in the passenger seat of a Range Rover wearing a tan blazer, shirt and black glasses as Prince Andrew, who was wearing a navy jumper over a red shirt, drove them out of the complex.
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It comes after HELLO! confirmed she had not been invited to attend King Charles's coronation next month - despite the fact that her daughters, Princess Beatrice and Princess Eugenie, will be there.
Very little information about the guest list has been revealed – it was only recently revealed that Prince Harry would be attending, albeit without his wife Meghan Markle and their children.
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But Sarah herself hinted she hadn't made the cut during an appearance on Loose Women last month. Whilst promoting her new novel on the show, she spoke of her plans for the big day.
"I personally will be having a little tea room and coronation chicken sandwich and putting out the bunting, that's what I'm going to be doing. Because that would make me very happy,” Sarah said. "I also love to watch it on the telly because you hear a lot on the telly.
"The commentators are always good and then everyone, all the family come back, because remember I am divorced from him [Prince Andrew] so I don't expect… you can't have it both ways, you can’t be divorced and then say, 'I want this…' [You're in] or you're out."
She continued: "I think it's really great to be supportive big time and then when all the family come home, I know all the ins and outs from commentators on television!
While Sarah will watch the ceremony from afar, a source close to Sarah confirmed that later in the day, she will be reunited with various members of the family for a private celebration.