The more I look at it, the less I think it is nickeled (but I have zero experience with nickeled firearms...)

the gun was proofed twice: once in London prior to 1924 (with this time fraime, we can assume it was imported new and proofed on entry in Great Britain.) 
This may improve our knowledge of the timeframe for these guns? 69040 would have had to be produced before 1924.


It was then reproofed in Birmingham prior to 1954 (presumably after it was "Parkerrifled")

So most certainly not a "very rare" gun  , but a genuine and complete 414 with a history of shooting in Great Britain that can still outshoot my eyes