I see that the white tape on the butt mentions 5L-4242 as having gone to Englandtoo. Looking at the fore-end number (pic 2) I would imagine that someone has read the SL maker as 5L and added the 4242 to come up with this red herring.
The rifle number seems to be A-14242. Maybe DRP can tell us when BSA started to number their rifles commencing 3xxxx
But seeing the lightly etched rifle number A-14242, you can imagine the problems we encountered at our big workshops with 'lost' numbers once they'd gone through the system. The progress chasers and R&I staff (that's Receipts and Issues staff who were responsible for the control of the special stores such as rifles etc etc to you civvies.....) used to pull their hair out over 'lost or indistinct numbers. But I'll let you into a secret if you promise not to tell anyone...........
Look............ If 125 rifles came in as serial numbers X,Y and Z and so on. regardless of how many numbers were 'lost' in the bead blasting, phosphating, machine shop, workshop system, then 125 rifles went out with those numbers attached to 125 rifles. Whether they were on the SAME rifles was not a point that we were concerned about.
The same went for Bedford trucks. If 50 came in for a complete chassis up rebuild, then they were stripped down to the last nut and bolt and chassis and......, well.........., you get my drift!