Prince Philip tied the knot with Queen Elizabeth II over 70 years ago, but he was never crowned king.

The 97-year-old retired royal is simply known as the Duke of Edinburgh or as Her Majesty’s husband. It has been revealed that the dad of four was never crowned as the King of England due to a British law, which determines who is up next to the throne. The same also dictates what title a monarch’s wife or husband would have.

And in terms of succession, the law is focused on the blood and not the gender. But in terms of the spouses of members of the royal family, the law treats men and women differently.

When a male in the royal bloodline marries, his wife takes whatever is the female form of his title. As such, when Prince William becomes king, his wife, Kate Middleton, would be known either as queen or queen consort.

Years later, when Prince George becomes King, Middleton will take on a different title that would reflect that she has become a widow of a king and the monarch of the reigning monarch. This rule assumes that Middleton would outlive her husband.

Meanwhile, when the Queen’s father, George VI became King, his wife’s title became queen consort. But the then-queen consort was more popularly referred to as the Queen Mother.

But when a female in the royal bloodline marries a non-royal, her husband is not eligible to take the male form of his wife’s title. Marlene Koenig, a royal historian, said that there is no precedent for giving a peerage to the commoner husband of a princess on their wedding day.

This is the reason why Prince Philip was never known as king. He is not a royal, and it is his wife who has royal blood. The same thing may be said about Princess Eugenie and Jack Brooksbank. After she wed the commoner, Brooksbank was not named as Prince Jack.

Prince Philip
Pictured: Prince Philip leaves St George's Chapel after the wedding of Prince Harry, Duke of Sussex and The Duchess of Sussex at St Georges Chapel on May 19, 2018 in Windsor, England. Getty Images/Gareth Fuller-WPA Pool