"Following medical advice to rest for a few days, The Queen attended hospital on Wednesday afternoon for some preliminary investigations, returning to Windsor Castle at lunchtime today, and remains in good spirits," the Palace said in a statement on Oct. 21.
HELLO! UK's Emily Nash also tweeted the Queen returned to her desk on the afternoon of Oct. 21 and was "undertaking light duties."
"Medics are thought to have taken a cautious approach and she stayed overnight for practical reasons," she wrote.
The Queen is understood to have been back at her desk this afternoon and undertaking light duties. Medics are thought to have taken a cautious approach and she stayed overnight for practical reasons.
— Emily Nash (@emynash) October 21, 2021
The previous day, it was revealed Her Majesty had "reluctantly" accepted medical advice to rest for the next few days and had cancelled her planned trip to Northern Ireland that was to take place this week.
It's not known why the 95-year-old monarch's medical staff advised her to rest, but the decision to cancel the trip was understood not to be related to COVID-19.
The last time Her Majesty was reported to have been taken to hospital was 2013, when she spent time at King Edward VII's Hospital and was treated for gastroenteritis.
The Queen has had a busy few weeks. Her Majesty opened the Scottish Parliament in early October following the ending of her official break at her Balmoral estate in the Highlands.
A few days later, she stepped out at Windsor Castle to welcome the Royal Regiment of the Canadian Artillery on the 150th anniversary of the first elements of the Canadian military being created.
On Oct. 7, she travelled back to London for her first engagement at Buckingham Palace since the start of the pandemic, where she and Prince Edward launched the baton relay for the 2022 Birmingham Commonwealth Games.
Last week, we saw her and Princess Anne attend a service of thanksgiving at Westminster Abbey to mark the centenary of the Royal British Legion. At that engagement, Her Majesty used a walking stick for the first time in 17 years, which is understood to be for her comfort.
Two days later, she travelled to Wales to open the Senedd, or Welsh Parliament, with Prince Charles and Duchess Camilla, and over the weekend she attended the Champions Day at Ascot. On Oct. 19, she hosted a reception at Windsor Castle to mark the start of the Global Investment Summit.
Her Majesty is still scheduled to attend the COP26 climate change conference in Glasgow. It launches Oct. 31 and runs through Nov. 12, and will be attended by other members of the Royal Family, such as Charles.