Queen Elizabeth's 90-year-old husband spent Christmas Day in a hospital bed after successful surgery to clear a blocked heart artery, missing the royal family's celebrations at its rural Sandringham estate in eastern England.
Buckingham Palace said Prince Philip, Britain's longest serving consort, was in "good spirits", but he is likely to have to spend much of the holiday season in a heart and chest clinic while doctors monitor his early recovery.
Philip's grandchildren, including Prince William and Prince Harry, visited the Papworth hospital near Cambridge to wish their grandfather well after Christmas lunch on Sunday.
The Queen had seen her husband, along with their four children, on Christmas Eve, a day after Philip was rushed to hospital suffering from chest pains.
By coincidence, Elizabeth's annual Christmas Day address, recorded before Philip was taken ill, stressed the importance of the family bond in times of crisis.
"We've seen that it's in hardship that we often find strength from our families," she said. "Families, friends and communities often find a source of courage rising up from within."
Despite his age, Philip has been in generally good health this year, seeing through a hectic schedule which included the wedding of William and Catherine Middleton, a jaunt to Australia and a visit from US President Barack Obama.
On turning 90 in June, he said he was looking forward to slowing down a little, but the Queen, 85, celebrates her 60th year on the throne in 2012, which will involve a busy tour across Britain and several other high-profile engagements.
The rest of the royals, including William and Catherine and this year's other newly-wed royal couple, Zara Phillips and England rugby player Mike Tindall, attended a Christmas Day church service at Sandringham.
They appeared relaxed, with some of the clan smiling and chatting as they entered the church. Unusually large crowds greeted them in mild winter air, eager for a glimpse of the Queen and the recently married couples.
After the service, Elizabeth met scores of patiently waiting children, calling on the help of some of the younger royals to cope with a stream of flowers, gifts and good wishes for Philip.
Known for a sometimes brusque manner and pointed wit, Philip is a central figure in the House of Windsor with a reputation as a fiercely loyal consort who prefers outdoor pursuits to introspection.
Born on the Greek island of Corfu in 1921, Philip served in Britain's Royal Navy before marrying Elizabeth in 1947.
Britain's tabloid newspapers have revelled in recounting his many public gaffes. He once told British students in China: "If you stay here much longer, you'll be slitty-eyed."
He had attended a lunch for staff a week ago and was said to have been on "very good form".
However, in a BBC interview to mark his 90th birthday in June, he had said he was hoping for a quieter life in older age.
"I reckon I've done my bit," he said. "I want to enjoy myself a bit now with less responsibility, less frantic rushing about, less preparation, less trying to think of something to say."