Just to add to Abasmajor's details. Interestingly the bible would seem to confirm that your rifle (series 7) was manufactured week ending 18/09/'71 . The first "A" prefix batch 6930 to 39 are noted in the factory ledger as "super" so were Supertarget models week ending 18/10/'68. I'm sitting here hoping yours is the Supertarget

Also interesting your other Mk lll could be series 4 if the serial number is impressed into the stock under the action. This practice stopped at 32000 around 1959.
The series 5 appeared 1961 with the dumbbell shape 'scope rail. Rarer versions had the 'scope rail "waisted" on one flank only and are a collectable quirk for some.

Whichever they are enjoy. Loves 'em. Jules