I will always stick by MK as the venue, big stars or no. I still remember coming by the show one day, not even knowing it was on, and saying "Wow! Its just like those conventions I've wanted to attend all my life. Except I can afford to attend this one!!"
Anyhow, about the stars, If you take all the "big name" stars off to London, then surely thats being prejudiced against some actors? I mean, who's to say the stars won't read this forum and say "What? You mean I've been asked to go to MK but not London? Cheeky swines!". It kind of pushes actors into the category of "Big stars" and "partial stars", and I don't think anyone here wants to do that.