King Charles III's coronation: Prince William's key role revealed

Prince William to represent royal family’s loyalty to King Charles III with historic vow at the coronation on May 6.

The Prince of Wales will step forward at Westminster Abbey on Saturday and pledge his loyalty and allegiance to the monarch during the landmark ceremony.

Soon after Charles is officially crowned, the prince will kneel before the monarch and place his hands between the hands of the King and say: "I, William, Prince of Wales, pledge my loyalty to you and faith and truth I will bear unto you, as your liege man of life and limb. So help me God."

Kate Middleton's husband's words, called the Homage of Royal Blood, echo the vow made by Prince Philip to his wife Queen Elizabeth in 1953 when he also vowed to be her "liege man of life and limb."

The "words of fealty" and William's role has been confirmed in the liturgy of the coronation service released by the office of the Archbishop of Canterbury at Lambeth Palace.

William is the only royal who will pay his respects in this way in the service. The future king will also appear during the coronation service as the Stole Royal and the Robe Royal are brought to the King. William will assist the Baroness Merron and bishops in putting the robe on King Charles.

Kate and William received massive applause and greetings from the royal fans as they shared a romantic image of themselves to mark their 12th wedding anniversary on Saturday.