Mike,
When trying to research this grenade I looked into the possibility of it being British made. I was unable to conclude it to be British but the following extract (last line) from the 1915 OB Annual Report was encouraging:
"Rifle Grenades RL Design 23017 and 23143
Director of Artillery 19.7.15 asked for drawings and Specifications of the rifle grenade to RL Design 22473 and 20.7.15 asked the Board to carry out trials.
Chief Inspector Woolwich 20.7.15 stated that RL Design 22473 was merely a drawing of the German Service Grenade, and drawings and Specifications were not available.
He recommended that the modified form of this grenade shown on CIW Design 2108 be adopted for trials.
[…]"
I will see if I have the drawing CIW 2108.
When trying to research this grenade I looked into the possibility of it being British made. I was unable to conclude it to be British but the following extract (last line) from the 1915 OB Annual Report was encouraging:
"Rifle Grenades RL Design 23017 and 23143
Director of Artillery 19.7.15 asked for drawings and Specifications of the rifle grenade to RL Design 22473 and 20.7.15 asked the Board to carry out trials.
Chief Inspector Woolwich 20.7.15 stated that RL Design 22473 was merely a drawing of the German Service Grenade, and drawings and Specifications were not available.
He recommended that the modified form of this grenade shown on CIW Design 2108 be adopted for trials.
[…]"
I will see if I have the drawing CIW 2108.