My Mark 111 as shown in above photos has a different bolt and is not matching, but has the early firing pin.
I did check three Mark 1*** rifles with new Irish serial numbers and a Mark 1** IP, none had the number on the cocking piece.
I have a BSA 1906 Mark 1*** with the original bolt and '06 dated barrel and matching rear sight and fore-end wood. The rifle's serial number is s over 87176 and the cocking piece is
s over 77425, bolt is 87176 over s. I did find a number cocking piece but not matching !Attachment 68856Attachment 68857