The Queen's sickness was first announced on Friday, and she spent yesterday resting at Windsor.
Her Majesty had been due to attend a Welsh military celebration in Swansea during the country's St David's Day celebrations on Saturday, but was forced to cancel the plans.
The Queen, who is 86, has undertaken a number of engagements during the last week.
On Tuesday she met the Archbishop of Canterbury at Buckingham Palace, and on Thursday she presented a host of Olympic stars with honours during an investiture ceremony.
More top news
The Duke of Cambridge followed in his mother's footsteps today as he visited Commonwealth War Graves in Japan.
Arsenal legend Thierry Henry says it would be a dream to manage the club one day, but admits he's got to learn his trade first.
Across most of England and Wales it will be a clear, chilly night and Friday morning will start off cold but bright until cloud builds up.