When I had a mix of British and Japanese bikes, I used to have a photocopy on my garage wall of all the spanner sizes in thou and mm - metric, AF, WHIT, BSF&C.. Came from a book my dad nicked out of Villiets' library when he left the cimpany in 1970. Amazed at how many could be used for summat eks, eg fir those times when you needed TWO of the same spanner.
Gave the book to a friend when he got a dmw deemster (say what?).