Thanks John and Tony for the info re. the Sportsmatch TO6C 13mm dovetail scope mounts - a set will be going on order tonight.
Current finances only allow for 1 set, though I could really do with at least 3 sets (4 x 1960's & 70's HW35's, Brummy BSA Lightning XL Tactical, Mercury Challenger, Superstar etc.).

Regards, Alastair