Prince William opened up on the Apple Fitness+ podcast ‘Time to Walk’ about what happens behind closed doors at the royal family’s annual Christmas morning church service at St. Mary Magdalene on the grounds of the Sandringham estate.

The former royal staffer says that when it comes to the holidays, Prince William will switch things up to include his in-laws down the road. "When William becomes King, the Middletons will be with them," Burrell predicts. "They will have Christmases at Sandringham and the Middletons will be there."

Prince William and Kate Middleton joined the rest of the royal family for their annual Christmas walk in Sandringham on Christmas day, and were accompanied by Prince William's step siblings, Laura Lopes (aka his " secret sister ") and Tom Parker Bowles.