"I can honestly say I shall treasure this my entire life."
A frenzy saw royal fans flocking to snap up the tours.
The update comes a month after Kate released an emotional video.
A smiling Charles, 75, accompanied by Queen Camilla, shook hands with scores of people gathered outside St George's Chapel.
A research team linked 45 social media accounts posting bogus claims about the princess to a Kremlin-affiliated disinformation campaign.
"It is for me a great sadness that I cannot be with you all today."
"He can't get on and do everything that he wants to be able to do."
It comes after the Princess of Wales revealed she had been diagnosed with cancer.
Prince William will continue to juggle caring for his wife and children while maintaining his public schedule.
