It has long been the case that far more ads are shown before movies in the UK than in the US or Canada. Yes, I know the North American crowd thinks they're getting a whole lot of ads these days, but it's not yet to the point it's long since been in the UK, where many people don't even bother entering the theater until a good fifteen minutes after scheduled starting time. Still, before tonight, I think the largest number of ads I counted before a film was 12, the largest number of previews 9 (Although I may be forgetting some higher numbers, the highest numbers have all been in that ballpark.)
Tonight, I finally saw Harry Potter and the Goblet of Fire. There were twenty ads before the modest six previews began.
In related trivia, what on earth is the role of a "Head of Crowd Tuition"?