Catherine’s brother also wrote on Instagram that he was “incredibly proud” of his sister, saying he was “honored” to take the test with her.
“Two years ago I told you that we would climb this mountain together,” he wrote in his post.
“We talked about climbing mountains while you were in the hospital and the incredible healing power nature can have on both the body and mind.”
He continued: “Seeing how far you have come is just inspiring. Your strength, resilience and determination as the most amazing mother, wife, daughter and sister inspires me and so many others every single day.”
Having completed the task, the princess paid tribute to the charity as “a place that means a lot to me and whose care and expertise makes a difference in the lives of many people.”
Catherine conquered the English Scafell Pike, the Scottish Ben Nevis and finished at the top of Yr Wyddfa, where the reunion took place.