When we had the thread going a little while back .... I put the Vernier & thread gauge on mine .... I came to the size of 1/2" UNF !!
Some folk thought it likeley that they were M12 metric fine .... Tried a known metric fine nut on one of mine & it didn't fit.
If I had to lay a £10 note on the line .... I would plump for the UNF option
If I had to lay someone else's £10 on the line ..... I'd choose both
