Bill
If you look at the post named "damascus explained" on page 52 in the middle of the page Drew Hause has a section from page 27 of Dallas's book on Purdey which shows this symbol Purdey stamped on each barrel they made. It looks like a small "a" followed by a different looking capital "E". You"ll see what I mean on "damascus explained". Can you check your gun to see if this stamp marking is on each barrel? Must be on the underside somewhere. Let me know. Thanks
Found a few spare minutes and got the Purdey from the vault. It does NOT have the letters you are interested in. BUT, it does have JW on the barrel flats, I'm sure they are for James Whitworth.
The letters you are interested in may only appear on Damascus barrels--- mine are fluid pressed steel.
Bill