Quoting directly from my 'best' reference on these records (Nigel Brown's British Gunmakers - Vol.1 London) :-
"W.J. Jeffrey's system of gun numbers was dealt with by allocating numbers in blocks. This means that one block might cover a much larger span of years than another or may be previous in date. I have, therefore, recorded the serial numbers in numerical sequence by their blocks together with the span of years covered by that block. For detailed reference it will be necessary to apply to J. Roberts & Son (Gunmakers) Ltd, who own the Jeffery name and holds the original record books."
This means, for example, that gun numbers 25291 thru 25600 cover the years 1929 thru 1939. Making this even more of a puzzle numbers 24982 thru 25282 were used 1913-1915 and 25601 thru 25900 were used 1917-1922. A very confusing system, to me anyway, but at the time it was devised doubtless someone had it all worked out. Fortunately, as LGF has discovered, Roberts do have more detailed records available.
The original poster's gun with # 35526, falls within the span 35441 - 35940 which Brown gives as 1929 to 1931.
As regards Proof Marks, there are many publications in print and on the net that reference English & foreign marks.
The booklet produced by Birmingham & London Proof Houses is entitled "Notes on the proof of shotguns and other small arms". The copy I have dates from 1976 and is not particularly informative but does give some foreign marks in addition to the English ones. The best and most comprehensive reference I have is again in Nigel Brown's 3 volume set on British gunmakers. Brown only covers English marks but there are various references on line, some being more accurate than others.
The original poster's gun shows Birmingham proof marks and the detail of the marks places the gun in the period 1925 -1954. The main change from previous marks (1904 rules) was the addition of chamber length.
Will attempt to post a quick guide to Proof Marks later.
Last edited by 300846; 11/26/12 07:47 AM.