Hello,
I have no idea if this is the same person, but I found this in Fold3.
British Jewry Book of Honour.
Pte. Amstell, H - 6107
Roll of men at the Depot,
38th- 40th Battalion Royal Fusiliers ("Judeans") - February 1919.
The month and year are the same as your man.
See here -
https://www.fold3.com/image/537878721?rec=614504315
Alex