I too have an Atkin, it's a Spring Opener made sometime in the years of 1926 - 1927 per the serial numbers listed in Atkin Grant and Lang by Don Masters. If I am seeing your serial number correct as 1733 according to the book it was made between 1902 and 1904.
When I purchased mine it also had a magnificent stock and I assumed it was a replacement. But a year ago it broke the left lock cocking spring and the Gunsmith told me the stock was original.
I love my Atkin and prefer it over my Purdey and Boss. It is the number "1" of a pair as well.
Your friend can go to the web site "Matched Pairs" and I beleive the guy is named John. He has listed serial numbers of lost guns he is activally looking for. My gun's mate was not listed.
Afew years ago I picked up a nice HJ Hussey Imperial Ejector here locally. After digging around and putting out feelers I found the other mate and it belonged to one of our on members here on this forum. After contacting and emailing him he was not interested in mine and at the time I could not afford his but he was not selling anyway.
But one day he contacted me about selling his Hussey. By that time I had sold mine to a good friend. After discussion with my friend and getting them two together my friend now owns the pair.
And yes I have tried to buy them and he's not selling either and probably never will.
