King Charles, accompanied by his sister Princess Anne - Royal Colonel of the regiment - has presented the new sovereign’s standard to the Blues and Royals, a cavalry regiment of the British Army, in the quadrangle at Buckingham Palace, said a statement.
Speaking on the occasion, King Charles expressed his pride in the troopers in a speech at the palace.
Earlier this s week, The Princess Royal hosted Investiture Ceremonies at Buckingham Palace and Windsor Castle where multiple people including cricketer Moeen Ali received honors.
Prince Anne is admired by millions of royal fans for her dedication to the royal duties and her family.
She is also respected for standing by her brother King Charles after the death of their mother Queen Elizabeth.
The Queen died in September last year at the age of 95 at a time when Prince Harry and Prince Andrew had already created problems for the royal family and the new king needed support of his family members.
Princess Royal, is the second child and only daughter of Queen Elizabeth II and Prince Philip, Duke of Edinburgh, and the only sister of King Charles III.
Anne is 17th in the line of succession to the British throne and has been Princess Royal since 1987