The Duke of Edinburgh remains in hospital after being told he should rest as he recovers from a bladder infection.
Prince Philip has been in Aberdeen Royal Infirmary since Wednesday when he was taken by ambulance from Balmoral after falling ill.
Philip, 91, had been holidaying with the Queen when he started to feel unwell.
He is suffering from a recurrence of the infection that led to him missing some of the Diamond Jubilee celebrations.
Buckingham Palace say the Royal family are in constant touch with him but are not visiting on Friday as he continues to recuperate.
Doctors have not said when the Duke will be discharged but he is said to be "responding well to treatment".
He and the Queen travelled to Balmoral for their annual summer break after attending a number of Olympic events.
They were at the Opening Ceremony on July 27 and toured the Olympic Park the next day, before watching granddaughter Zara Phillips compete in the eventing on July 29.
Philip had appeared to be in good spirits as he attended events at Cowes Week on the Isle of Wight, in his role as Admiral and member of the Royal Yacht Squadron earlier this week.
The latest health scare comes two-and-a-half months after he was taken to hospital with a bladder infection following the Diamond Jubilee Pageant on the River Thames.
He also underwent a successful procedure to clear a blocked coronary artery last December over Christmas, which grandson Prince Harry said had given him a "new spurt of life".
Meanwhile, the Ministry of Defence has confirmed a search and rescue helicopter was sent to help take the Duke to hospital on Wednesday but was unable to meet the ambulance he was travelling in due to bad weather.