Wow, what an interesting thought - Rowling writing Dr Who, I see why they asked her because I think she could do it but anyways I respect her decision and I can't wait for the next book!
Hmm... I cannot see where the idea for her to do it came from; most the writers they asked are established fans, I am not sure if I ever heard that about her. Not that this means it was a bad idea, just it seems out of sync.
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"We've got maybe seconds before Darth Rosenberg grinds everybody into Jawa burgers and not one of you buds has the midi-chlorians to stop her!"
Didn't she mention Dr Who in the Jeremy Paxman interview she did? Either way though, she could be or have been a fan, she was around at the right time for the craze.