Top Ender Giggles - Name Confusion

Whilst watching the Sky One TV Coverage of the premier of Harry Potter and The Deathly Hallows Part Two we were commenting on how different the actor's and actresses who play characters in the film look in real life. I told Top Ender to look out for Emma Watson, who plays Hermione because she has had her hair cut really short. When Emma Watson came on screen I said;

"Look, that's Emma Watson, see I told you she had her hair cut!"
"Hermione you mean?" asked Top Ender
"No, Emma Watson, that is her real name" I answered
"I thought you said Emma whatshername!" answered Top Ender

Top Ender in Gryffindor costume for the midnight release of the book Harry Potter and the Deathly Hallows in 2007

I'm not entirely sure why I am posting this other than Daddy told me too, because he likes the idea of Emma Whatsername...