Inside Queen Elizabeth and Prince Philip's Seven-Decade Marriage

They have the longest royal marriage in history – and that’s because Queen Elizabeth and Prince Philip, who celebrated their 72nd anniversary this year, have an ideal dynamic, says their biographer Gyles Brandreth.

Brandreth, author of 2004’s Portrait of a Marriage, recently offered insight into the royal couple’s seven-decade union.

Here’s what makes their remarkable marriage work:

1. He makes her laugh

With his dry wit and famously uncensored humor, Philip has long been the person who can most bring a smile to the Queen’s face. During a visit to Wales on Tuesday, he showed his humor once again in an exchange with 10-year-old Katrin Powell.

“He asked us if we could speak Welsh, and we said yes,” she told reporters. “He said, ‘You must have really good brains to speak Welsh.’ “

“The Duke of Edinburgh is a funny man,” Brandreth wrote in The Radio Times. “He is the fellow who said, ‘If you ever see a man opening the car door for his wife, it’s either a new car or a new wife.’ He has been making the Queen laugh for more than 70 years.”

2. He is his own man

Since vowing at her 1953 coronation to be the Queen’s “liege man of life and limb,” Philip has dutifully fulfilled her role as the Queen’s consort – but that doesn’t mean he takes a back seat in their relationship.

“The Queen wears the crown, but her husband wears the trousers,” writes Brandreth. “He is the power behind the throne: steadfast, never-failingly supportive.”

What’s more, “because she is the Queen, no one in the world treats Elizabeth II entirely normally – except for Prince Philip,” says the biographer. “Conversely, the Queen is the only person in the world who can say to the Duke of Edinburgh, ‘Oh Philip, do shut up.’ And she does.”

3. They accept each other’s differences

Philip, who “wants to do what he did when he was 55”, his grandson Peter Phillips recently said, “is dynamic, outgoing, adventurous, challenging,” observes Brandreth. The Queen, on the other hand, “is conservative, placid, content to do things as they have been done before. He reads a good deal, where she doesn’t. He has infinite patience. He has rather less . . . As a couple they are allies, but that doesn’t mean they don’t have their differences.”