I did some searching (as a result of my ignorance on the subject) and found this tid bit of info in a discussion on BOCN, posted by AE501:
“Thank you for the improved photo.
I find it pays to read books that you have had for years.
All is now clear to me at least. Perhaps some already knew the answer. This is a genuine case.
The original British 15 pounder was a BL gun developed from the 12 pounder and both were the Field Artillery standard gun in 1899. These had bagged cordite charges.
News came in 1897 that the French had a revolutionary 75mm QF gun which had recoil and recuperator systems, on a slide principle.
The French at that time were perceived to be Britain’s potential main enemy.
We had nothing on the drawing board at that time with anything like that potential.
In 1900 the German public were very anti British, in part due to the Anglo Boer War, not to mention the naval arms race. The British public felt much the same about Germany.
But needs must, so in great secrecy on both sides, we purchased 18 artillery batteries worth of 15 pounder QF guns and equipment, from the engineering firm of Erhardt, Dusseldorf, which obviously included QF ammunition. Every reference to Erhardt was omitted from the ammunition and equipment. These guns also operated on a slide system and had recoil and recuperation…”
So it would seem your projectile is indeed of German manufacture, circa very early 1900’s , with the projectile base markings following British protocol! The above quote may also explains why there are no identification markings on the fuze.