The Queen is continuing her recovery in hospital after she was admitted with symptoms of gasrtoenteritis, Buckingham Palace said.
She is reportedly in "good spirits", despite being forced to pull out of engagements for the coming week.
The Queen was struck with the stomach bug on Friday and admitted to King Edward VII's Hospital in London on Saturday as a "precaution", but is "otherwise in good health", according to a spokesman.
She was well enough earlier in the day to meet an employee privately to award her a medal for long service.
The Queen is likely to stay at the hospital for two days, so has been forced to cancel a visit to HMS Lancaster in London on Monday, and a reception for MPs and MEPs at Buckingham Palace will now be hosted by another member of the Royal Family.