Tim Larkin, 2011 Black Belt Magazine Hall of Famer and Self Defense Instructor of the year was stopped from boarding a plane in Las Vegas headed for jolly old England due, as stated in a U.K. Home Office Secretary, was that he was deemed a security risk for his plans to teach his brand of reality based self defense at an annual even he was to be the keynote speaker at. He hadn't planned on doing anything illegal and in fact in other sources has confirmed that he has a 12 year history of doing these seminars and providing instruction but a recent ban is coming in to effect because of what his students might do.
It's a crock of crap though, anyone familiar with the man and his work knows he has always stated that even someone who is highly trained should first attempt to deescalate a situation or escape before violence is actively engaged. As of this post I'm joining Black Belt Magazine in beseeching the U.K. in reconsidering this ludicrous ban. The man teaches valuable skills in self defense in a responsible manner and they should be making that more accessible, not less so.