Her laughter makes him frown, because he's not well dressed. He remembers how she looked when they first met, in a fancy dress. He'd just got it into his head that was sort of the Pandorian style. As it turns out, the opposite is true.

"Alright. Please nothing... really weird."

And with that he goes off to find her something that might just pass in London. A dress and a vest-thing. Not exactly suitable for an audience with the queen, but that's not what they're trying to do.