The Duke of Edinburgh has wasted the nighttime in infirmary after being admitted as a “precautionary measure”.
Prince Philip, 98, passed from the Queen’s Sandringham Estate, in Norfolk, to London’s King Edward VII Hospital on Friday morning.
Buckingham Palace said the admission was for “observation and therapy with regard to a pre-existing condition”.
The BBC’s Simon Jones said the Royal Family will be hoping the duke is able to return to Sandringham for Christmas.
The palace said the duke went to hospital on the advice of his doctor. But it refused to confirm or disclaim reports the duke was flown to London by helicopter and then driven by car for the last part of the journey.
The duke moved into hospital and is expected to remain there for a few days.
As he was travelling to London, the Queen was on her path to Sandringham for the beginnings of her Christmas break.
She caught the 10:42 GMT Great Northern service from London’s King’s Cross and was later painted stepping off the learn at King’s Lynn railway station.
At the scene
Simon Jones, BBC News, outside King Edward VII Hospital
While Prince Philip remains in hospital, the surrounding streets are full of TV satellite trucks all over the world, waiting to broadcast the latest news on his condition.
Buckingham Palace hasn’t exhausted any further explanations overnight – though that’s to be expected. The Duke is known as a profoundly private person who doesn’t like a fuss.
The palace won’t want to give a operating commentary on any care he might be receiving.
For as long as it’s unclear though why he’s been admitted to hospital, opinion will continue – and one key question is whether he’ll be well enough to join the Queen at Sandringham for Christmas.
Although there’s concern about the duke’s condition, in palace curves there’s not a sense of alarm. I think we see that by the fact that the Queen has decided to continue with her Christmas habits rather than remaining here in London.
Last Christmas, Prince Philip missed the royals’ traditional Christmas Day trip to church.