Mate in 2: Extremely Hard
I think it's an awesome puzzle/trivia question... to make it fair you have to say something like: this puzzle relies on the <1932 interpretation of the castling rule.
(I just made up 1932 as an example... was there ever really a time when this mode of castling would have been a possible legitimate reading of the "official" rules of chess?)
This has been done before, and there's another little piece of humor included on this link as well:
http://en.wikipedia.org/wiki/Joke_chess_problem#Offbeat_interpretations_of_the_rules_of_chess
tricky tricky :)......but thats akin to the magic trick of sawing a woman in half...at first glance youre like.."how did he just do that!!", then once you take a good look you feel stupid for buying into that idea in the first place.....nice smoke and mirrors buddy :D