17476 is a Former Terry Buffum gun:
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=157099Terry's 2007 comment: "
I hope I can find a picture of a similar gun I just consigned to Greg Martin. #17476, Purdey thumb push opener, also with the London and Paris addresses. The dual cities markings seem to only appear on his earliest guns; some later guns carry two street numbers on New Oxford, London. Nigel Brown lists a numberr of his addresses, but not this dual cities marking. I think it is circa 1860 based on looking at a number of his guns." Not sure the sale went through since he consigned it 10 years later.
Here is the definitive line on EM Reilly which I authored (the gun is mislabeled in the chronology as 17474).
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=436555&page=3I believe 17476 was likely numbered in Fall 1871. (1st EM Reilly with Paris on the rib I've found is 15270 - He opened his Paris store in Feb 1868; Reilly was numbering about 50 guns a month. 17474 is 2,200 guns up the list...about 3 years 8 months after Feb 1868 = Oct 1871). (edit: It admittedly may be a few months later...his production pre-1867 was about 40 a month prior to his amazing success at the Paris 1867 show...see the comments on the Reilly Martini-Henry.)