I have two Jeffries 38-button concertinas, whose fretworks are identical and whose components (inside and out) appear to be of nearly-identical vintage. One is dated extraordinarily precisely, in that it came with its original "Bought of Charles Jeffries / English & Anglo German Concertina Manufacturer / 23 Praed Street, Paddington W" sales receipt, dated March 11th 1897, cost £6 / 18 / 6, and signed by "C Jeffries" (presumably Junior, as Senior was by accounts I've read illiterate and signed with "X").
The above-described is a C/G. The right fretwork (but not the left) says "C JEFFRIES" "MAKER" amidst the buttons. There is also a "C JEFFRIES" "MAKER" stamp on one side of the wooden end on the left side (adjacent to the strap screw).
The other is a G/D. The right fretwork (but not the left) bears an identical "C JEFFRIES" "MAKER" amidst the buttons. (There is no stamp on any of the wood endframes.) The look of the reedpans, reed shoes, reeds, and levers is not different from the C/G, though the tops of the metal buttons on the G/D are more rounded than on the C/G. (Other parts of the G/D - pads, many valves, and most notably bellows - are by the Dippers, whereas on the C/G appear to be original.) In every respect I can tell, the reedpans and reeds for the G/D appear original and with G/D being the original keys.
Given all of this, I have always assumed a date of 1890s for the G/D being made, as my understanding is that the stamping on the fretwork changed to include "23 PRAED ST" not many years into the 1900s. (Nothing inside gives me the impression the G/D reedpans and reeds were a later substitution.) Robin Harrison may have an estimate of his own (as I bought this from him). And of course, I welcome all of your opinions as well!
Edited by wayman, 17 March 2018 - 05:12 AM.