Prince William and his wife Catherine will become the Prince and Princess of Wales, making her the first woman to use the title since the death of Diana a quarter of a century ago.
Known as the Duke of Cambridge until yesterday, William added the Duchy of Cornwall – a Dukedom automatically inherited by the heir to the throne – on the death of Queen Elizabeth II.
However, becoming the Prince of Wales, the traditional principle title used by the next in line, was in the gift of the new King, who made the announcement during an address to the nation from Buckingham Palace.
William will be given the title through the mechanism of Letters Patent, a legal written order issued by the monarch, with an investiture ceremony likely to be held in Wales next year.
King Charles III was made the Prince of Wales by his mother as a nine-year-old, with his investiture not held until nearly 11 years later at Caernarfon Castle.
He spent ten weeks leading up to his day learning about Welsh culture, history and language and he made his address in Welsh.
“Today, I am proud to create him Prince of Wales, Tywysog Cymru, the country whose title I have been so greatly privileged to bear during so much of my life and duty,” said the King.
“With Catherine beside him, our new Prince and Princess of Wales will, I know, continue to inspire and lead our national conversations, helping to bring the marginal to the centre ground where vital help can be given.
“As my heir, William now assumes the Scottish titles which have meant so much to me.
“He succeeds me as Duke of Cornwall and takes on the responsibilities for the Duchy of Cornwall which I have undertaken for more than five decades.
The King, in his first remarks since the death of his mother at Balmoral, paid tribute to his wife, during a heartfelt and eloquent address to the nation, watched by a TV audience in excess of 25 million.
“This is also a time of change for my family. I count on the loving help of my darling wife Camilla. In recognition of her own loyal public service since our marriage 17 years ago, she becomes my Queen Consort,” he added
“I know she will bring to the demands of her new role the steadfast devotion to duty on which I have come to rely so much.
“My life will of course change as I take up my new responsibilities.
“It will no longer be possible for me to give so much of my time and energies to the charities and issues for which I care so deeply.
“But I know this important work will go on in the trusted hands of others.”
It is expected other changes to titles will be confirmed in the days ahead, it’s well known the Queen’s wish was for her youngest son, Prince Edward, to succeed Prince Philip as the Duke of Edinburgh, with her daughter-in-law Sophie, with who she was particularly close, becoming the Duchess of Edinburgh.
King Charles III also used the his speech to reach out to increasingly estranged younger son Prince Harry.
“I express my love for Prince Harry and Meghan as they continue to build their lives overseas,” he said.