Even the royals take the train! On Friday, Kate Middleton and Prince William tried to blend in with the crowd at King's Cross railway station in London, donning baseball caps and casual clothes after a trip to Norfolk, England. With her hair in a ponytail, Kate layered up in a loose button-down shirt, sweater, jacket, and skinny jeans. Meanwhile, William stayed cool in a dress shirt and relaxed-fit jeans. Although the couple didn't bring Prince George with them, they were joined by another member of their immediate family: their adorable cocker spaniel, Lupo. The casual outing comes at a bittersweet time for the royals, since Sunday marks the 17th anniversary of Princess Diana's tragic death . Later this year, William will start a new chapter of his career  by becoming an air ambulance pilot, for which he will start training in September.