Miniature Thorn Needle compared to BCN through microscope

[IainP1]

Very nice to see all these super close-up images, thank you for posting them.
I have seen pictures of electrical pickups from the 1940s, or maybe they were even from the 1950s, that used steel needles held in with a thumbscrew. Would those be the kind of pickups the tiny thorn needles would be used in and if so, would they also have also been used to play LPs?

Yes. Many of them, probably the great majority of such pickups (earlier types) would take full sized thorn needles, whereas most of those form the late 40s or 50s would only fit miniature thorns.

I don't make miniature BCN thorns myself (it's possible but very labour intensive indeed), however I do keep various new-old-stock types.

Labour intensive: I can imagine! I'm amazed how small they actually are: