Britain's Prince Philip was in "good spirits" after his wife Queen Elizabeth II and his children visited him in hospital on Saturday as he recovered from heart surgery.
The 90-year-old, Britain's longest serving royal consort, was airlifted on Friday from the Sandringham estate where the royals were celebrating Christmas, and taken to hospital for an operation to unblock a coronary artery.
His four children - heir to the throne Prince Charles, Prince Andrew, Prince Edward and Princess Anne - joined the queen at Philip's bedside at Papworth hospital near Cambridge in eastern England, Buckingham Palace said.
"The Duke of Edinburgh had a good night and is in good spirits but he is eager to leave," a Buckingham Palace spokeswoman told reporters outside the hospital on Saturday.
He was however set to remain in hospital under observation for a "short period", the palace said.
The prince will not attend the traditional Christmas Day church service at St Mary Magdalene Church on the Sandringham estate, the palace announced, and reports suggested he could be kept in hospital for up to five days.
The health scare means Philip is likely to miss much of the traditional festivities at Sandringham, where Prince William's new wife Catherine was set to spend her first Christmas with the other royals.
He may also miss hosting his traditional Boxing Day shoot.
The Greek-born prince Philip married then Princess Elizabeth 64 years ago, and has become a national institution almost as much for his often brusque comments as for his support for the monarch.
He announced after celebrating his 90th birthday this year that he would be winding down his royal duties, although with the queen's diamond jubilee coming up in 2012 it promises to be a busy year.
British Prime Minister David Cameron's Downing Street office said he had been "kept informed of the situation and wishes the Duke of Edinburgh a very speedy recovery."
Buckingham Palace said Prince Philip suffered chest pains late Friday and was taken by helicopter from Sandringham to the hospital, where tests revealed that he had a blocked coronary artery.
"This was treated successfully by the minimally invasive procedure of coronary stenting," it said in a statement.
The procedure involves inserting a tube-like device called a stent into the blocked artery to open it up and help restore a healthy blood flow. It is often performed under local anaesthetic.
Palace officials refused to say whether he had had a heart attack, but Iqbal Malik, a consultant at Imperial College London, said "he probably was having a heart attack" which was successfully aborted.
On Saturday Britain's normally stoical royals made an unusual dash to Prince Philip's bedside.
The 85-year-old queen, her younger sons Andrew and Edward and her daughter Anne flew by helicopter from Sandringham to the hospital just before 1100 GMT (10pm AEDT) and spent 45 minutes with him, the palace spokeswoman said.
Charles and his second wife Camilla arrived later at the hospital.
The traditional Christmas morning church service was "going ahead as planned" and the royal family's Christmas plans remained unchanged, she added.
The queen is set to stress the importance of family when she delivers her annual televised Christmas Day message.
Philip has been in largely good health and joined his wife on an 11-day tour of Australia three months ago, but pulled out of a trip to Italy in October nursing a cold.