Prince Philip's death certificate reveals cause of his death

Prince Philip's official cause of death has surfaced, and it's simply stated as "old age" in his death certificate, according to report.

The Duke of Edinburgh had a number of ailments in his later years, including a heart scare just months before he passed. However, in his final days he succomed to "old age."

The Queen's husband, who remained in hospital weeks before his sad demise, died of nothing more than just being an old-timer, according to his official longtime palace doctor.

According to experts, old age is acceptable for someone over 80 who had one doctor look over his care for years ... and if there's no other identifiable disease or injury responsible for the death.

Philip tied the knot with the future queen in 1947 and served steadfastly by her side for more than seven decades, as she became the longest-serving monarch in British history.

Prince Philip, 99, died last month, and the Royal Family held a grand funeral procession for him. Prince Harry flew in from the States for the ceremony and got some face time in with his brother and father.