King Charles to honour Queen Elizabeth on her 100th Birthday with 'national address' It has been reported that King Charles will pay tribute to Queen Elizabeth and "renew his vow of service" in a heartfelt message on April 21, marking what would have been her 100th birthday. 18 April 2026 King Charles will reportedly honour the late Queen Elizabeth with a message to mark her 100th birthday. The then-Prince Charles and Queen Elizabeth in 2022 It has been said that the 77-year-old monarch will deliver his heartfelt recorded address to the nation on Tuesday (21.04.