Prince Philip celebrates 97th birthday

As Britain formally celebrated Queen Elizabeth's 92nd birthday Saturday in the annual Trooping the Colour military spectacle, one familiar face was noticeably absent from the monarch’s carriage and by her side on the balcony at Buckingham Palace.

Prince Philip, Duke of Edinburgh, is celebrating his 97th birthday Sunday.

Fittingly, as husband to the Queen, the world’s oldest head of state and the longest-serving monarch in British history, Philip is the longest-serving consort in British history.

But he did not participate in the festivities in central London Saturday, following his retirement from royal duties in August last year following 65 years of public service.

The couple married on November 20, 1947, before Elizabeth became Queen following the death of her father, King George VI.

Philip and Elizabeth celebrated more than 70 years of marriage in their anniversary in 2017.

There have been concerns for his health, and the Duke has been admitted to the hospital for a number of ailments in recent years, including hip and abdominal surgery and bladder infections.

Most recently, he underwent a hip replacement operation in April, which kept him in the hospital for several weeks.

Philip was born Prince Philip of Greece and Denmark in 1921 in Corfu, Greece. He joined the Royal Navy as a cadet just before World War II broke out in 1939.

Having met the young Princess Elizabeth at a wedding in 1934, they courted before he asked her father for her hand in marriage.

He renounced his European titles and became a naturalized British subject ahead of their wedding in 1947. He was made Duke of Edinburgh by King George VI.