Prince Philip, the Duke of Edinburgh, is said to be in 'good spirits' while recovering from heart surgery and was visited by his wife Queen Elizabeth in hospital.
The monarch arrived by helicopter near Papworth Hospital, and was then ferried by vehicle to the cardiothoracic unit.
After a visit lasting 45 minutes, the Queen left the facility and returned by helicopter to Sandringham House in Norfolk, where the Royal Family gathered to celebrate Christmas, Sky News reports.
The 90-year-old husband of Queen Elizabeth II recently underwent an "invasive procedure of coronary stenting" after being taken to hospital with chest pains.
Speaking outside the hospital, Buckingham Palace spokeswoman Ailsa Anderson said that, "the Duke of Edinburgh had a good night and is in good spirits, but he is eager to leave".
"Tomorrow's church service is going ahead as planned and we don't anticipate changes to the Royal Family's Christmas celebrations," the spokeswoman added.
The palace said that Prince Philip would remain under observation for a "short period".