Threads? Whitworth standard was published in 1841, so had to be some home brew oddity.
Should the restoration effort entail Whitworth bolts, I shall donate my 1958 Jaguar wrenches. Dunno why I still have them....
We, ( Royal we, lol) where using threads in the middle ages to hold some of the great Cathedrals up ,using iron rods and ‘chains’.
Amiens is a true beneficiary of said addition.
The threads would no doubt have been “ of pitches diverse”.