Sorry englishman_ca, missed this early, from what I have seen (on like 20 Lee Speed (BSA Sporters) & LSA Sporters) nearly all had that lug, with most being drilled & tapped for a screw, set inside a Diamond shaped ferrule.

Cool old rifle you have there, I almost bought a BSA Officers Carbine some time ago, it had the tang sliding safety .

Thank you for sharing your one with us !