For a day event it's actually quite expensive, though it's the first of its kind and getting those guests over are what probably drove it up.

EDIT: Actually make might have more to do with it being for.charity and.a one time event. We don't get much pr alumni over here after all.

EDIT v2: Also Goddamn those autograph prices
prices not sure about going now unless they announce more about the event.

Yeah, since its the first of its kind and a charity thing I was a bit more forgiving of the £35 entry for a day event. But with £15-20 per autograph/photo and (for me at least) travel costs to think about, the entry suddenly becomes a bit harder to swallow.