Sir Clive Alderton, the most senior aide to King Charles, has announced that he will step down next year.Sir Clive is Charles’ and Queen Camilla’s principal private secretary.His resignation will coincide with his 60th birthday in May, and will come 20 years after he first joined the royal household.In a message to staff, he said: “It has been the greatest imaginable honour to serve the King and Queen in my present role through such historic times and with unforgettable humour along the way.“That support will continue, in a less formal capacity, for all of my life.”