The go to manufacturer for most of the UK vehicle locks was a firm called Wilmot Breeden, like BSA, Birmingham based. Their brand name on the keys was UNION, and the keys had the lock number stamped on them. Surprisingly the matching number can be sometimes
found on the face of the lock! Yes, it was a different time then. The keys still turn up in close down sales of established garages, autojumbles and the usual suspects.
So, if the lady looks through any keys left, an original UNION key is a likely contender.
Swarfy.