Shame there is no serial no, otherwise I can't tell if that is LincolnJ H model or an early BSA. I believe they changed the breech tap retaining plate from serial 2626, improved mod variant from then on.
BSA through breech tap retaining screw was bigger so this does not look original unless it is a Lincoln Jeffries variant of some sort. It would be hard to find a tap that would fit that early rifle well if the tap isn't the original one.
If it was the H mod then it would be worth a punt. Does look like a nice project for someone to restore that lady to its former glory.
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HW97k, HW98, Diana mod 36, BSA improved Mod D, FWB 80, HW45