Prince William appointed a former Government diplomat as his private secretary on Friday, as he returned to royal duties this week following his father's cancer diagnosis.
Ian Patrick, who has also worked for former Liberal Democrat leader Lord Ashdown, will take up the role, Kensington Palace revealed.
Ian worked under Lord Ashdown when he was in Bosnia from 2002 to 2006 before joining the Foreign, Commonwealth and Development Office.
He is also a trustee for Crohn’s & Colitis UK, a charity for the two main forms of inflammatory bowel disease.
The Prince, 41, resumed his royal duties earlier this week after taking time off to support his family, following the Princess of Wales' planned abdominal surgery.
William hosted an investiture ceremony at Windsor Castle on Wednesday before attending London's Air Ambulance charity gala dinner later that evening where he thanked the public for their words of support for his father and wife.
Taking to the stage, he said: "I'd like to take this opportunity to say thank you ... for the kind messages of support for Catherine and for my father, especially in recent days. It means a great deal to us all."
"It's fair to say the past few weeks have had a rather 'medical' focus. So I thought I'd come to an air ambulance function to get away from it all".
It was announced on Monday evening that Charles would be undergoing regular treatment for an unspecified cancer, found during his recent hospital stay for a procedure on an enlarged prostate.
The cancer the King has is yet to be disclosed, but Queen Camilla shared an update on the King's health when she stepped out on Thursday for the first time since news of his diagnosis.
Talking to Ben Abbott, 40, a critical care paramedic with Wiltshire Air Ambulance, Camilla revealed: "He's doing extremely well under the circumstances, he’s very touched by all the letters and the messages the public have been sending from everywhere – that’s very cheering."