Queen Elizabeth II and Prince Philip are members of the British royal family but they still have some normal experiences -- like when they were walked in on in an intimate position.

The moment is detailed in the 2011 biography "Young Prince Philip: His Turbulent Early Life" written by Philip Eade. According to Express, the book revealed that the embarrassing moment occurred during the early stages of the royal couple's marriage.

"Philip had his own bedroom next-door to Elizabeth’s, an arrangement common to a great many upper-class couples at that time," Eade explained and added that, according to historian Robert Lacey, there was a door built into the wall between the two bedrooms which allowed the two to "enjoy the visitation rituals which that system involves."

Eade went on to write that it was James MacDonald, a royal valet, who walked into Prince Philip's room and was "embarrassed to see the princess in her husband’s bed."

"While she was wearing her usual silk nightgown, Prince Philip appeared to be naked," MacDonald added. "He didn’t care at all."

READ: Queen Elizabeth Brought Prince Philip To Tears For This Reason

Queen Elizabeth and Prince Philip have been married for 72 years now and while a lot around them has changed, one thing hasn't. The royals still sleep in separate bedrooms.

"In England, the upper class always have had separate bedrooms," Philip's cousin, Lady Pamela Hicks, once revealed.

"You don’t want to be bothered with snoring or someone flinging a leg around," she continued. "Then when you are feeling cosy you share your room sometimes. It is lovely to be able to choose."

Separate bedrooms aren't just a British concept, though. Miami-based businessman Eric Borukhin explained to Vanity Fair that the act of sleeping separately is actually a luxury.

"It’s a matter of convenience if you can afford it," he said. "If you can have that extra room, it’s basically a luxury."

Britain's Queen Elizabeth II and Prince Philip
Britain's Queen Elizabeth II and Prince Philip are photographed. AFP/Fiona HANSON