After missing Christmas with the Royal Family because of a heart ailment, Britain's Prince Philip was back on his feet at the queen's country estate Sandringham on Tuesday.

"He looks well," royal commentator Richard Fitzwilliams told CTV's Canada AM. "He is a person of tremendous physicality for his age."

The 90-year-old husband of Queen Elizabeth smiled and waved to onlookers when he left hospital in a Range Rover after spending four nights recovering from a coronary stent procedure that cleared a blocked artery. He had been taken to hospital Friday after suffering chest pains.

"The procedure was a success and he was eager to leave hospital," Fitzwilliams said. "If you consider the massive year ahead, he is going to want to get back to normal as quickly as possible."

Next year's Diamond Jubilee, marking the Queen's 60th year on the throne, will involve a series of trips to England, Scotland, Wales and Northern Ireland and hundreds of events.

"Planners have taken a great deal of care, remembering the Queen is 85 and he is 90," Fitzwilliams said. "There will be no more than two or three events a day."

In light of the fact that Prince Philip had decided to slow down his active schedule after turning 90, the Queen has decided to dispatch her children and grandchildren on the more grueling overseas trips to mark the jubilee.

Still, Fitzwilliams added, "his idea of slowing down was to cut 20 of the 830 institutions he is linked to. He will still do 300 events a year. ... He has got this iron constitution."

Royal commentator Peter McNally of McGill University said ten years ago, the Queen and Prince Philip visited Canada, Australia and other Commonwealth countries for her Golden Jubilee.

"But whether that slowdown is because of the Duke or because of the Queen, isn't clear," McNally told CTV News Channel. "Remember the Queen is 85, she'll be 86 in April. I suspect that this has as much to do with her situation as his."

It was the first time in many years that the Royal Family's patriarch had missed the traditional Christmas festivities at Sandringham, which included a church service Christmas morning and the prince's shooting party on Boxing Day.

McNally said the Duke has a mixed reputation within the British public over his penchant for putting his foot in his mouth with politically incorrect comments.

Still, McNally said, the Queen relies heavily on Prince Philip, and rarely appears in public without him.

"If he isn't there to support her," he said, "the concern will be how will the Queen go about her obligations."

With files from The Associated Press