Many thanks Hampden Project, Whitley_Project and Anon for solving both sources. The Mustang item could be a missing ‘mislaid’ piece from ‘Little Zippie’ – need to check. So, the inspection stamp is a Gloster ‘G5’, it isn’t very clear on the item. Pity those parts have no history, but at least they now have a type identity.
PM sent Rocketeer.