King Charles III has started off an incredibly busy and historic day, which began with him being formally proclaimed monarch at the Accession Council. After the death of Queen Elizabeth II on Thursday, the former Prince of Wales automatically became King but the Accession Council was called as soon as possible to make it official.
A wave of national transformation is now in full swing as once-in-a-generation procedures that have been decades in the planning are put into action. His Majesty will be meeting many powerful figures today as he is holding audiences at Buckingham Palace, including a private meeting with no media present.
For the latest updates as the world mourns the Queen and King Charles III's reign begins, follow our live blog.
The King's audiences will all take place in the 1884 Room, where his late mother received many distinguished visitors during her reign.
At 2pm, the King will meet the Archbishop of Canterbury, Justin Welby, who said the Queen had "no fear of death" when he last saw her in June.
Next up at 2.30pm, His Majesty will have a second audience with new Prime Minister Liz Truss, but this time she will be joined by Members of the Cabinet.
Leaders of the opposition parties, including Labour's Keir Starmer, will be received at 3pm.
His final audience at 4pm will be with the Dean of Westminster, Reverend Dr David Hoyle, who was appointed by the Queen in June 2019.
This morning, Charles' role as King and his regal name were confirmed at the Accession Council, which was televised for the first time ever.
More than 200 privy councillors, made up of mostly senior politicians past and present including former prime ministers, were present to hear the Clerk of the Council read the proclamation.
The King was declared by the Accession Council in front of many attendees, including Queen Consort Camilla, heir to the throne Prince William and several former Prime Ministers.
He made a personal declaration on the death of the Queen saying: "I know how deeply you and the entire nation, and I think I may say the whole world, sympathise with me in this irreparable loss we have all suffered."
Charles followed a tradition going back centuries by signing the declaration with 'Charles R' - but he added the letter for a different reason to his late mother.
The Queen used the signature 'Elizabeth R' on official documents, which actually stands for 'regina' and means 'queen' in Latin.
Because Charles is King, his 'R' stands for 'rex', so he will now write 'Charles R' when he puts pen to paper.
The new King has a busy few days ahead, as he is now preparing to embark on a tour of the country in the days before the funeral to meet his new subjects as millions around Britain unite in their sorrow.
On Monday, Charles will receive the motion of condolence at Westminster Hall before starting his UK tour with a visit to the Scottish parliament and a service at St Giles Cathedral in Edinburgh.
Tuesday will see the King arrive in Northern Ireland, where he will receive another motion of condolence at Hillsborough Castle and attend a service at St Anne's Cathedral in Belfast.
He will then travel to Wales on Friday to receive another motion of condolence at the Welsh parliament and attend a service at Llandaff Cathedral in Cardiff.
The King will hold another formal audience with the Prime Minister on Sunday - with the Queen's funeral expected to take place the day after.
The Queen will be buried in the castle’s King George VI Memorial Chapel and senior members of the Royal Family are expected to follow behind the coffin, which will be drawn to the Abbey on a gun carriage pulled on ropes by sailors rather than horses.
King Charles addressed the nation for the first time in a pre-recorded video message on Friday, which was incredibly well received by the public and left some in tears.
He announced that William and his wife, Kate Middleton, would become the new Prince and Princess of Wales, as well as praising his wife and new Queen Consort Camilla.
He also sent love to his youngest son and his wife Meghan Markle, saying: "I want also to express my love for Harry and Meghan as they continue to build their lives overseas."
The biggest tribute was obviously for his "darling mama" and his late father Prince Philip, as he ended his speech by saying: "As you begin your last great journey to join my dear late Papa, I want simply to say this: thank you.
"Thank you for your love and devotion to our family and to the family of nations you have served so diligently all these years. May 'flights of Angels sing thee to thy rest'."
* This weekend, the Daily Mirror and Sunday Mirror celebrate the life of Her Majesty the Queen with a commemorative special filled with all the key moments from Britain’s longest reigning monarch. Be sure to pick up your copy of the Daily Mirror and Sunday Mirror to get poth pullouts.
You can leave your tributes to Queen Elizabeth II here