1921 British artillery primer

The seller said that her grandfather brought it from the Great War (WWI). I don’t see WWI dates on it. Which shell/gun did this primer service?

This is a British No2 Mk 1VN primer that I have in 3Pr Hotchkiss Navy cases (47x376).
Also noted on cut-down cases only 205mm long (blanks?)
Made by Kings Norton 4/21 and filled by RL 9/21 so post WW1.
I have these primers dated and used up till 1940 at least. No15 primers also used.