Nice one Joe.
In fact, now that you mention it we have three different knurling types with the same maker. Mine, Bill's & yours are all different.
I have often suspected that many of the badge/pin manufacturers bought in the attaching pins & fixings in bulk from specialist makers. Somewhere (although at the moment it escapes me exactly where
) I've seen a period add for them... I'll have to have a hunt around.
Cheers
Don
