If you take it apart, there are enough places that a "true" Purdey is marked that you could find your answer.
I have 104 years old true Purdey. What marks do you expect to find to determ its true Purdey or not?
Full set of London proof marks, both barrel tubes have their own Whitworth' numbers besides Purdey s/number.
There two letters located on action under stock wood. I don't remember letters now, but Purdey's people told me its actioner maker letters. S/number on forend. Thats it. No more letters or numbers anywhere on the gun.
I have to say some parts of "vikram" Purdey very looks like true Purdey. For instance top lever and safety button, exact copies in details of my Purdey top lever and button. Not sure about barrels replacement, but top rib been redone and thats for sure.