The Queen's appearance among world leaders at the COP26 summit is hanging in the balance as she waits for guidance and 'test results' from doctors after being admitted to hospital this week.
The monarch, 95, had planned to join Prince Charles and Prince William at the COP26 conference in Scotland on November 1.
But royal sources have indicated her appearance at the event is said to 'hang in the balance', after she spent a night under the care of specialist doctors at the King Edward VII hospital in Marylebone, London.
The Palace said that the monarch was discharged on Thursday morning and returned to Windsor Castle at lunchtime, where she is expected to recuperate for the rest of the week.
The Queen's appearance among world leaders at the COP26 summit in Glasgow is hanging 'in the balance' as she waits for guidance and 'test results' from doctors after being admitted to hospital this week
It is understood the trip to the private King Edward VII's Hospital in London (pictured) on Wednesday afternoon was expected to be for a short stay for some 'preliminary investigations'
The monarch, 95, had planned to join Prince Charles and Prince William at the COP26 conference in Scotland on November 1
MailOnline understands that any future commitments, such as COP26, were still in the Queen's diary but would have to be confirmed nearer the time.
It is believed that her private office is waiting for the results of the preliminary tests and will see how the elderly monarch feels over the next few days.
The global climate summit is set to take place in Glasgow from Sunday October 31, to Friday November 12.
But Royal doctors ordered Her Majesty to rest and advised her to miss a trip to Northern Ireland this week, sparking speculation about the reason for the eleventh-hour cancellation.
The Queen was understood to be in 'good spirits' and back at her desk reading her official government red boxes on Thursday. Her admission is understood not to have been related to coronavirus.
Buckingham Palace said medics took an 'understandably cautious approach', adding the Queen's admission was for 'practical reasons', with just a week remaining before she was due to appear at COP26.
The monarch returned home to Windsor Castle on Thursday afternoon and is due to commence a schedule of 'light duties' once