The Duke of Edinburgh has spent a fourth night in hospital after missing the Royal Family's Christmas celebrations and annual Boxing Day shoot following a heart scare.
Prince Philip was taken to Papworth Hospital near Cambridge on Friday night after he complained of chest pains.
The 90-year old underwent treatment for a blocked coronary artery and has been kept in hospital as a precaution.
The Duke had hoped to be discharged from hospital in time for Monday's shoot, which he normally leads, but remained under observation in hospital. Despite the disappointment he was said to be in good spirits.
A Buckingham Palace spokesman said: "The Duke of Edinburgh continues to make good progress from the procedure. He remains in hospital under observation and in good spirits."
Following tests, doctors discovered a blocked artery and he underwent a "minimally invasive procedure of coronary stenting", which was declared a success, but he has been kept in hospital so doctors can keep a close eye on his recovery.
This is the most serious health scare suffered by the Duke, who is known for being robust and active.
He has shunned the pursuits of typical pensioners and even as an octogenarian continued to compete in demanding carriage driving competitions.
Philip's most recent illness was an uncharacteristic cold in October that forced him to pull out of an overnight stay in Italy for the launch of the ARC Green Pilgrimage Network.
He had just completed a busy 11-day official royal tour to Australia with the Queen, 85, that saw them visit Perth, Melbourne, Canberra and Brisbane.
His next formal engagement is a dinner at the Scott Polar Research Institute at the University of Cambridge on January 17.
The Duke was visited in hospital by his grandchildren the Duke of Cambridge and Prince Harry on Christmas Day.
The Queen is being briefed on her husband's condition continually.
