Have seen (and held) an L42 that has the rifle serial No on the butt (not the scope No), its the real McCoy and does check out.
Had a look last night to see if I had the scope No, of the one that was in an auction last year but only found the rifle # (I did make a note of the scope #, as it was not mentioned in the auction catalogue), the scope looked a bit erm.......well, not quite right, I guess this has been turned round and come back in the market with some form of story. Just waiting conformation regarding the movements of the said rifle....