Queen Elizabeth II's husband is expected to spend a second night in a hospital where he is recovering from a heart procedure, palace officials said Saturday.
Prince Philip, 90, had a coronary stent put in late Friday to fix a blocked artery, though the palace has refused to say if he had a heart attack.
On Saturday, Philip _ also known as the Duke of Edinburgh _ received visits from the queen and his four children at Papworth Hospital, where he was admitted after experiencing chest pains at the queen's Sandringham estate in Norfolk.
The illness has cast a shadow over the royal family's traditional Christmas gathering at Sandringham _ the first to include Prince William's new wife, Catherine. Buckingham Palace said Philip is not expected to attend church Sunday with his family, but that the service will go on as planned.
A helicopter brought Elizabeth to her husband's side at Papworth Hospital, about 70 miles (115 kilometers) from London, shortly after 11 a.m. (1100 GMT, 6 a.m. EST) on Saturday. She was accompanied by three of her children _ Princess Anne, Prince Edward and Prince Andrew.
Philip is "in good spirits, but he is eager to leave," Buckingham Palace said. After spending 45 minutes with Philip, the royals traveled back to Sandringham by helicopter, it added.
The palace said Prince Charles and his wife, Camilla, arrived by car at the hospital 45 minutes after the queen for a separate visit and that no other family members were expected to visit on Saturday.
Doctors said Philip could have had a heart attack, but without more information it was impossible to know for sure.
Coronary stenting is standard procedure both to fend off a heart attack or save a patient already in the midst of one, said Dr. Allan Schwartz, chief of cardiology at New York-Presbyterian, Columbia University Medical Center.
Philip, who in November marked 64 years of marriage to the queen, has been known to enjoy good health throughout his life and rarely misses royal engagements. Upon his 90th birthday in June, he announced plans to cut back his official duties.
In addition to well-wishers gathered outside Papworth Hospital, Prime Minister David Cameron also offered his support to Philip.
"The prime minister has been kept informed of the situation and wishes the Duke of Edinburgh a very speedy recovery," Cameron's office said.
Doctors say that some patients can leave the hospital a day after a similar medical procedure, but the palace said it does not know when Philip will be discharged. It said the prince remains "under observation" and that he is having a "short stay" in the hospital.
Members of the royal family were due to start arriving at Sandringham, where Philip had been since Monday, throughout the day Saturday.
While members of the public who gather each year to catch a glimpse of the royals walking to Sunday's traditional church services will most likely not see Philip, Buckingham Palace said it does not expect changes to the rest of the royal family's Christmas agenda.
Another key part of the royal family's Christmas celebrations is the queen's annual message to the nation, which this year will focus on family and community.
The queen has made a prerecorded Christmas broadcast on radio since 1952 and on television since 1957. She writes the speeches herself, and the broadcasts mark the rare occasion on which the queen voices her own opinion without government consultation.
Cassandra Vinograd can be reached at http://twitter.com/CassVinograd