It is said that prior to her hospital stay last week Queen Elizabeth II had not been feeling well since early September.

The British monarch spent the summer holiday in the Scottish Highlands at Balmoral Castle. Members of the Royal Family were also spotted heading to the estate including Prince Andrew, Sarah Ferguson, and their youngest daughter Princess Eugenie, who was seen with her son August and husband Jack Brooksbank.

But Queen Elizabeth II reportedly was not able to fully enjoy the holiday, especially her love for horseback riding. A Balmoral source told The Sun that she was "in quite a bit of discomfort."

"She adores riding and it has been part of her ritual for most of her life. She has been extremely disappointed not to go riding since the beginning of September," the insider said.

The 95-year old is under medical advice to rest and under strict orders to refrain from exerting too much effort in walking, driving, or riding. She has been told to carry out "light duties" only, as such, she has only been doing video calls from her desk.

This means she has not been able to walk her corgis too as she continues to recuperate. She usually takes them out around Frogmore Gardens near Windsor Castle. Shortly after Prince Philip died, she was photographed driving her Jaguar out of the castle gates towards the gardens, which is said to be her favourite place to contemplate.

However, Queen Elizabeth II has reportedly not fully given up horse riding. She plans to get back on the saddle soon in spring after she has recuperated.

"The Queen is sad she can not get out on her horse, which is one of her favourite pastimes, but she is resting and taking every precaution to get back to full fitness," another source told the Mirror.

It is said that Queen Elizabeth II was "knackered" with her packed schedule of public and private engagements. She had to stay overnight at King Edward VII Hospital to run some tests for an unknown health condition. Her private secretary has also since been advised to trim down her schedule to important engagements only.

Queen Elizabeth II
Queen Elizabeth II had an overnight stay in hospital after a packed schedule in early October Photo: POOL / Victoria Jones