Looks totally legit in every way, and a nice example in seemingly great condition. It even falls into the correct serial number ranger for Fazakerley, according to Stratton. As others have already stated, the forend tip looks "odd" in its taper; and, just get a correct 800 yard rear sight (via eBay, Sarco, or GPC, they run up to $70 or so) or even a "type 2" rear flip sight (a mere $8 or so). Saying it's fake because of the rear sight is like saying a Porsche ain't a Porsche because it has tires that a Volkswagen uses on it.

Nice find!