This has come up in discussion with fellow painters a bunch of times. I finally decided to check my Humbrol enamel tin collection. My initial guess was from the 1980s, since that was when I switched from the cheap small glass Testor pots to Humbrol enamel tins. This was before the historical miniature wargaming hobby when I was just painting up plastic model kits.
Well...after checking, I have two tins from the 1970s. I must have bought them in the 1980s from stock that was still on the shelf. Maybe even into the early 1990s. These have English and French languages because I bought these in Canada.
Here is my earlier post on my Humbrol paints: LINK
