It comes after Charles III was appointed King following the death of the nation’s longest-reigning monarch, Elizabeth II.
King Charles III acceded to the throne immediately on the death of Elizabeth II, at the age of 96 in the sanctuary of Balmoral Castle.
The Queen’s son and successor King Charles III spoke of his grief soon after Buckingham Palace announced the death of the 96-year-old monarch, who died “peacefully” on Thursday afternoon at Balmoral.
There were cheers from the crowds as the King’s state Bentley arrived at the gates of the Palace.
He stepped from the car to greet the hundreds of well-wishers gathered outside.
Charles shook hands with countless members of the public lined up behind a barrier, thanking them for their good wishes.
Cheers rang out at Buckingham Palace as the King and Queen arrived, along with shouts of “God save the King”.
Queen Elizabeth: Updates as Buckingham Palace announces the death of the Queen
Speaking to the BBC royal correspondent Richard Sumner said: “The whole policy of the palace has always been understatement and I’ve always suspected that possibly there was more than a mobility problem concerned here.”
“When you’re 96, of course you can’t expect to have the health of a 25-year-old.
The Queen is the only British monarch to have celebrated a Platinum Jubilee.
Her reign has stretched from the post-war years into a new millennium and a radically altered 21st century.
In her twilight era, she has been setting her affairs in order, using her Jubilee message to endorse her daughter-in-law, the Duchess of Cornwall, once a royal mistress, as a future queen to be crowned at the Prince of Wales’s side when he becomes king.
Former Labour prime minister Sir Tony Blair said he is “deeply concerned” by the news about the Queen’s health.
“It is deeply concerning to hear today’s news from Buckingham Palace,” Sir Tony said in a statement posted to Twitter.
“My thoughts and prayers are with Her Majesty the Queen and her family at this worrying time.”
During her Platinum Jubilee celebrations, the Queen only travelled to Buckingham Palace twice, first for her Trooping the Colour balcony appearance and then for a finale after the pageant.
She secretly spent a night in hospital for tests in October and was ordered by doctors to rest for the next three months, missing the Remembrance Sunday Cenotaph service and Cop26 climate change talks.
A sign reading “no guard changing ceremony today” was in position outside Buckingham Palace on Thursday morning but was later removed by officials.
The “prayers of the nation” are with the Queen, the Archbishop of Canterbury has said, as the country’s leaders sent messages of support regarding the announcement that the monarch is under medical supervision.
The Archbishop of Canterbury has said the “prayers of the nation” are with the Queen.
“My prayers, and the prayers of people across the (Church of England) and the nation, are with Her Majesty The Queen today,” Justin Welby tweeted.
“May God’s presence strengthen and comfort Her Majesty, her family, and those who are caring for her at Balmoral.”