This is what Prince Philip sleeps in – and it’s not pyjamas!

Cape Town - A royal valet was left red-faced after he walked in on Prince Philip waking up in his birthday suit.

Prince Philip reportedly doesn’t believe in wearing pyjamas, which is why he sleeps naked, Express UK reported.

The 98-year-old monarch shares a connecting bedroom with his wife, Queen Elizabeth (93). She was visiting her husband when royal valet James MacDonald walked in at a rather awkward time, revealed former royal correspondent James Whitaker.

"When he walked into Philip’s bedroom one morning, royal valet James MacDonald was embarrassed to find Elizabeth in a silk nightgown and Philip naked," Whitaker explained.

While MacDonald was left in utter disbelief, Philip on the other hand "didn’t care at all."

"Pyjamas? Never wear the things," the Duke of Edinburgh is believed to have added.

This comes as no surprise especially after actor Matt Smith, who plays Prince Philip in popular Netflix royal series The Crown, stripped before getting into bed in one of the show’s scenes, Metro reported.

The royal pair reportedly sleep in two separate rooms to avoid each person’s snoring, which according to The Sun is an upper class tradition. But every now and then whenever the pair are feeling cosy they share a bed to cuddle.

Sources: Express UK, Metro, The Sun