Serial number is 41a and it is Enfield built, meaning that original proofs would have been through the London Proof House.
The BNP stamps are Birmingham Nitro Proof, put on in 1927, when the new barrel was installed. They worked over a LOT of WW1 rifles in the '20s, then scrapped a whole bunch right through to about '37 or '38 because it was well known that just as long as WE trashed our War Reserve rifles, that nice Mister Hitler would be happy to do likewise. NOT!
The strikeout marks I do NOT understand on this rifle. Wish we had a full photo of the action.
ENGLAND stamp was applied when the rifle was surplussed, after War Two.
.303" is the bore diameter, 2.222" is the maximum case length it was chambered for, 18.5 TONS followed by the little square and the two dots means 18.5 British Imperial Long Tons per square inch = 41,440 pounds per square inch, the WORKING pressure of Service ammunition. Proof loads were, of course, an overload and developed much higher pressure, but the rifles were marked with the SERVICE pressure of what they were SUPPOSED to be used with.
Stamps of E or ED with a crown above and a number below or beside are Enfield INSPECTORS' stamps. Somewhere, once upon a time, there was a list of who the Inspectors were and which Inspector used which stamp during which years. Likely, it was trashed when the old LE series went out of production in the 1950s. So much knowledge lost.
A real historical piece..... one that I would not mind owning at all.
Congratulations on your prize!