'My mother's reign was unequalled in its duration and its devotion'

During a poignant and sombre meeting of the Accession Council, the King spoke movingly about his mother and the grief his family is experiencing, but said the "sympathy expressed by so many to my sister and brothers" had been the "greatest consolation".

Watched by the Queen Consort, the new Prince of Wales and more than 200 privy counsellors - including six former prime ministers - the King pledged himself to the task now before him and the "heavy responsibilities of Sovereignty".

His mother would be his guide for the years ahead as he strived to "follow the inspiring example I have been set in upholding constitutional government", he added.

The day included a moment of pomp and pageantry with David White, Garter King of Arm, in his colourful regalia and flanked by other Officers of Arms and Sergeants at Arms, reading the proclamation of the new King from a balcony at St James's Palace.

Meanwhile, in Scotland the late Queen's other children, the Princess Royal, Duke of York and Earl of Wessex, and their families attended a service at Balmoral's Crathie Kirk where their mother regularly worshipped.

Afterwards, Anne, her husband Vice Admiral Sir Tim Laurence and her children Zara Tindall and Peter Phillips joined Andrew and his daughters, Princesses Beatrice and Eugenie, and Edward and the Countess of Wessex with their daughter Lady Louise, at the gates of Balmoral Castle to look at floral tributes left for the late monarch.

Eugenie wiped away tears at one point and was hugged by her father Andrew, and returned the comforting gesture.

Andrew Milligan/ PA Wire (Image: Andrew Milligan/ PA Wire)

Well-wishers outside Balmoral today following the death of Queen Elizabeth II on Thursday

Charles began his momentous day by discharging the "sorrowful duty" of announcing the death of his "beloved mother", and told the council: "I know how deeply you, the entire nation - and I think I may say the whole world - sympathise with me in the irreparable loss we have all suffered.

"It is the greatest consolation to me to know of the sympathy expressed by so many to my sister and brothers and that such overwhelming affection and support should be extended to our whole family in our loss."

Charles spoke of the late Queen's "selfless service", adding: "My mother's reign was unequalled in its duration, its dedication and its devotion. Even as we grieve, we give thanks for this most faithful life."

He went on to say: "I am deeply aware of this great inheritance and of the duties and heavy responsibilities of Sovereignty which have now passed to me. In taking up these responsibilities, I shall strive to follow the inspiring example I have been set in upholding constitutional Government and to seek the peace, harmony and prosperity of the peoples of these islands and of the Commonwealth Realms and Territories throughout the world."

The King ended by saying: "And in carrying out the heavy task that has been laid upon me, and to which I now dedicate what remains to me of my life, I pray for the guidance and help of Almighty God."

The historic event was broadcast for the first time, giving the world a first glimpse of an ancient ceremony dating back centuries and one of the first changes to convention instigated by the new King.

Following convention, Charles did not attend the first part of the ceremony when the clerk of the council Richard Tilbrook read the proclamation to the packed meeting that confirmed the new monarch.

He said: "...Prince Charles Philip Arthur George, is now, by the death of our late Sovereign of happy memory, become our only lawful and rightful liege lord, Charles III..."

The meeting was staged in the state rooms of St James's Palace, and the clerk declared to the room: "God Save the King," with the privy counsellors repeating the famous phrase.

The new monarch became King the moment his mother died, but an Accession Council must be convened following the death of a Sovereign - usually within 24 hours.

More than 200 privy councillors - a group of mostly senior politicians past and present, some members of the monarchy and other national figures - were present to hear the Clerk of the Council read the Accession Proclamation.

Among them were ex-prime ministers Sir John Major, Sir Tony Blair, Gordon Brown, David Cameron, Theresa May and Boris Johnson - Cabinet members, former Archbishops of Canterbury and York with everyone standing, a convention believed to have been established by Queen Victoria to keep such meetings short.

The current premier Liz Truss was part of the proceedings.