Would the real Royal family please stand up?

A couple nights ago on Dog Eat Dog (I really shouldn’t be so quick to admit that I watch these shows) the following trivia question was asked: What is the given name of the British royal heir? Simple.

But it suddenly occured to me that I couldn’t think of the surname of the Royal family. I got my mother involved, and one of her work colleagues tracked down a definitive source.

It’s probably not exactly what you think it is.