Members of the Royal Family have been summoned to the castle to be beside the Queen after doctors said they were concerned for her health.
All of the Queen's children have headed for Balmoral, as have Princes William and Harry.
Harry and Meghan had been in Germany today and were due to attend a WellChild event in London this evening (8 September) before the news of the Queen's health caused the need for her family members to travel to Balmoral.
A spokesperson had previously said: "The Duke and Duchess of Sussex will be travelling to Scotland."
However, it has since been confirmed that Meghan will stay in London, as will Prince William's wife Kate Middleton.
The Duke of Sussex will now travel alone to Balmoral to see his grandmother, however, she could travel up to Scotland to join the rest of the Royal Family at a later date.
Doctors have said the Queen 'remains comfortable' at Balmoral and royal physicians have recommended that she stays under their supervision.
The 96-year-old monarch was pictured on Tuesday (6 September) meeting new prime minister Liz Truss, but was unable to attend a virtual Privy Council yesterday.
The Queen also missed the annual Braemar Gathering highland games, which she usually attends, that were held last weekend.
A spokesperson for the palace said: "Following further evaluation this morning, the Queen’s doctors are concerned for Her Majesty’s health and have recommended she remain under medical supervision.
"The Queen remains comfortable and at Balmoral."
A crowd of well wishers has gathered outside Balmoral, and others have crowded outside Buckingham Palace.
The new prime minister said 'the whole country will be deeply concerned by the news from Buckingham Palace', while Labour leader Sir Keir Starmer said he was 'deeply worried' about the Queen and was hoping for her recovery.
Both Truss and Starmer were alerted to the Queen's condition while in the House of Commons today, as was speaker Sir Lindsay Hoyle, who said parliament 'send our best wishes to Her Majesty the Queen' and said she was 'in our thoughts and prayers at this moment'.
Other messages from figures around the world have been sent, with the White House saying US president Joe Biden's thoughts were with the Queen.
Canadian prime minister Justin Trudeau said the thoughts of he and 'Canadians across the country' were with the monarch, and they they were 'sending our best to the Royal Family'.
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