While the eyes of 2 billion viewers were glued to Kate's stunning gown and 9-foot train, Carson knows the groom has to look good too. To find out where Prince William most likely gets his clothes, Carson took a trip to London's Savile Row and the legendary military outfitter and bespoke tailor Gieves & Hawkes.
Watch Carson's tour of London's ultrafancy shopping district
Because no guest at a royal wedding would be caught without a couture hat that turns heads, Carson's next stop on his fashion tour of London is Philip Treacy's atelier. This famous hat designer has covered the heads of all sorts of royalty, from Princess Diana to Lady Gaga.
Browse this gallery of the best millinery of the royal wedding
Carson says he thinks Victoria Beckham was one of the best dressed of William and Kate's guests. "You're not supposed to be too flashy, that's kind of that whole English thing. You don't want to take it overboard," he says. "The other really weird thing that I didn't know was there's supposedly an unwritten rule that you're not allowed to wear the same color as the Queen. She was wearing yellow, and I noticed nobody else was. And I was like, does she tweet in the morning saying, 'Listen, I'm wearing buttercup'?"
Watch more of Carson's reaction to the royal wedding fashion