This looks like a typical folk art style of painting, similar to canalware but also to American Toleware patterns (on tinware) or Eastern European Folk Art. Usually painted in a formulaic manner, so fairly simple to do (as is canalware). Very pretty, much nicer than transfers for sure, but not so hard-wearing as you've found out Bernard.
Was this actually done "in house" at Bagley or was it decorated externally in the same way as I buy blanks to decorate? I know Angela's Bagley Glass book refers to in-house decorating, and I recall you saying you met the lady who painted the polks dots on Bagley items, but is there actual proof that the cold painting as here was done in house as well?