Why stick to horse races, afternoon tea and other stuffy royal events when you can tour the set of "Harry Potter"?

Prince Harry , Prince William and Kate Middleton made the most of their royal connections by getting a special tour of Warner Bros. Studios in Leavesden, Hertfordshire, on Friday. The playful threesome hit up Diagon Alley, got a wand session in the Gryffindor Common Room and even held a meeting (an actual one, for The Princes' Charities Forum) in Hogwarts' Great Hall.

Throughout the tour, the royals joked and played with all sorts of props -- given wooden wands to test out, Prince Harry immediately challenged his brother to a duel. Will joked later on , "Harrys just excited to see a real-life talking owl in the Harry Potter studios. I havent told him yet that Harry Potter is fictional, so please keep the secret for a little longer."

The group also investigated pieces from the "Batman" movies, including the giant "Batpod" motorcycle and the Batmobile. "You don't do baby seats for these cars, do you?" quipped William.

We bet not, which is a shame: Kate was looking more pregnant than ever, resting her hands on her tummy as she made her way around the studio. Given the laid-back nature of the day, the duchess made a savvy fashion choice: a 38 Topshop dress with a black Ralph Lauren jacket on top. (True story: We almost bought that Topshop dress just recently -- and it's still available right here .)

We just wish she and the boys had tried on some authentic Hogwarts robes.

Check out all the fun in the photos below.

UPDATE: Within an hour of her appearance , Kate's polka-dot Topshop dress sold out. As of now, you can only purchase it in burgundy. Darn Duchess Effect...

Want more? Be sure to check out HuffPost Style on Twitter , Facebook , Tumblr , Pinterest and Instagram at @HuffPostStyle.--Do you have a style story idea or tip? Email us at stylesubmissions@huffingtonpost.com. (PR pitches sent to this address will be ignored.)