Queen Elizabeth II’s husband was discharged from hospital on Sunday, after being treated for a chest infection.

After spending three nights in London's King Edward VII's Hospital, the 86-year-old prince is now resting at Windsor Castle.

Royal officials insisted that Prince Phillip’s hospitalization was only a cautionary measure and not an emergency.

The Duke of Edinburgh was admitted in hospital last Thursday, after a cold developed into a chest infection which caused him to miss the thanksgiving service at Windsor Castle for Sir Edmund Hillary, the first mountaineer to conquer Mount Everest.

The prince’s engagements and duties for Monday were also cancelled until his full recovery.

He is supposed to visit Dartmouth's Britannia Royal Naval College, together with the queen, on April 10.

Rumors that the Duke suffered from heart problems spread last year, but they were never confirmed. Patron of the British Heart Foundation, he is believed to take regular medication for his heart condition.

The Duke is known to be a very strong and energetic man, involved in many projects. He is patron of many organizations, including the World Wide Fund for Nature and The Duke of Edinburgh’s Award.

The prince has been the center of attention lately, as a jury was trying to establish a final verdict in the case of Princess Diana’s death. He was repeatedly accused by Dodi Al Fayed’s father, Mohamed Al Fayed, of planning the assassination of Princess Diana. However, coroner Scott Baker concluded that there was no evidence that any member of the royal family had been involved in the death of Princess Diana.

Prince Phillip married Queen Elizabeth II in 1947. Initially a royal Prince of Greece and Denmark, he gave up his titles before marriage.