Kate Middleton has fulfilled an emotional promise she made with her younger brother while undergoing cancer treatment.
James Middleton revealed the private pact in a July 5 Instagram post after joining his sister for the National Three Peaks Challenge. Princess Catherine completed the grueling hike in late June to raise money for The Royal Marsden Cancer Charity.
James shared a photo of himself embracing his sister and another of the pair with their family. Their parents, Carole and Michael Middleton, Prince William and the couple’s three children, Prince George, Princess Charlotte and Prince Louis, joined them for the special moment.
The challenge marked the fulfillment of a promise James made to his sister two years earlier while she was in the hospital.
Kate Middleton’s Brother Reveals Their Private Promise
James opened his message by sharing his pride in his older sister.
“I’m so incredibly proud of my darling sister ❤️⛰️,” he wrote.
He then revealed the conversations that led to their eventual climb together.
“Two years ago, I told you we’d climb this mountain together,” James continued. “We talked about climbing mountains while you were in hospital, and about the incredible healing power that nature can have for both the body and the mind.”
James said joining his sister for the challenge was especially meaningful because of the promise they had made.
“So it was such an honour to join you for your Three Peaks Challenge for the Royal Marsden Cancer Charity,” he wrote.
He also reflected on how far the Princess of Wales has come since undergoing treatment.
“Seeing how far you’ve come is nothing short of inspiring,” James added. “Your strength, resilience, and determination, all while being the most amazing mother, wife, daughter, and sister, inspire me and so many others every single day.”
He ended the message with a simple note to his sister.
“Keep being exactly who you are ✨,” he wrote.
Princess Catherine Took on Britain’s 3 Tallest Peaks
Princess Catherine completed the National Three Peaks Challenge by hiking the tallest mountains in Scotland, England and Wales within 24 hours.
The challenge included Ben Nevis, Scafell Pike and Snowdon. The full hike covered 23 miles and raised money for The Royal Marsden Cancer Charity.
The London-based charity supports cancer research and works to improve treatment for patients.
The princess explained why she decided to take on the challenge in a June 28 Instagram post.
“I have taken on the National Three Peaks Challenge, not simply as a physical endeavor but as a chance to explore life beyond diagnosis and to give something back,” she wrote.
The cause holds personal significance for her.
“The Royal Marsden is a place that holds great meaning for me and whose care and expertise are life-changing for so many people,” she continued. “Through this challenge, I want to raise awareness for the deeper impact of serious illness and the importance of holistic healthcare.”
One week later, the princess shared more photos from the challenge and thanked those who supported the charity. The images included moments with William and their children.
James Middleton Previously Promised His Family Would Be There for Kate
James has publicly supported his sister throughout her cancer journey.
Princess Catherine announced in March 2024 that she was undergoing treatment. Shortly afterward, James shared a childhood photo of the two of them.
“Over the years, we have climbed many mountains together. As a family, we will climb this one with you too ⛰️❤️,” he wrote at the time.
His message took on new meaning two years later when the siblings literally climbed a mountain together.
The princess completed chemotherapy in September 2024. In January 2025, she announced that she was in remission.
The Three Peaks Challenge brought the Middleton family together as she fulfilled the promise she and James had discussed during her treatment. For her younger brother, the experience also offered a chance to recognize the progress he had witnessed firsthand.
“Seeing how far you’ve come is nothing short of inspiring,” he wrote.
