Hmmmmm! I was taught that "thins" were the lower case i, upper case I and lower case l

Yes, you are correct in theory, but handset cases never had the correct thins in them after they'd been dissed into once by some ignorant and uncaring apprentice. Or handsetter for that matter! And if the handsetter was short of thins, he or she just grabbed a handful from a case of the same point size, regardless of the font.

Thins in the lino fonts came in one size for each point size, nothing to do with the width of any of the l or the i in any given font. I suppose we could have bought them for each font, but the two papers I worked for didn't bother. The lino thin mats were so fragile that we used to buy them by the hundred and people were threatened with death if they didn't hammer them flat when they got bent. You were only supposed to diss them permanently when the lugs broke off.