To me, a hotel either is a luxury hotel or it isn't one. The qualification, "By the standards of <name of city>, this is a luxury hotel" just isn't valid -- the top end is determined by global standards. It is perfectly valid to say, "This is one of the best hotels in <name of city>" but that doesn't make it luxury. And, in the case of the London IC, as pointed out above, even that weaker statement isn't true.