LEE ENFIELD RARE .22 TRAINER....W/PICS

[bros]

Looks like Lee-Enfield Rifle No.2 Mk.IV* Pattern (A.G.P. /Parker Rifled - Enfield No. 1 MkIII*) commercial training rifle.

Any thoughts what a "commercial training rifle" was used for......was this used in service? Who made this this crudely manufactured rear sight and was it most likely fitted by who?