Um, I don't think there were any Dutch people on ours (although I can't be sure).
The reason I've been on so many is I'm a member at the Club, so whenever I bring a guest to a game I usually get them to go on a tour (and as tours are free for members I tag along too).
This was actually the first tour I've been on, when there hasn't been a game on; what's interesting is that pretty much all of the 7 tours have been different, in terms of where they go, and the style of the tour guide too.
I know what you mean about it being a bit pricey, but I think they try to run it on a self-funding basis, and from memory, I think, last year's accounts indicated they didn't really make much (if any) profit on the tours. If you bear in mind it's normally £3 to just go into the museum (and the tour ticket entitles you to free entry of the museum) I guess it makes it seem, marginally, a bit better value.