One might add that Welsh does indeed share a subdivision (Brythonic) of Celtic, including Breton (living), Cornish (dead, but with an active revival movement), and Cumbrian (really most sincerely dead), all descended from ancient British.
While that is true, it is also true that the word “Aryan” has a very complicated history, having meant at various times, “Iranian”, “North Indian”, and “Indo-Iranian”, as well as “Indo-European” and “Nazi ideal”.
As a boy, my great-grandmother would always warn me about “minding my Ps and Qs”. When I asked she explained it stood for Pleases and Thank Qs. I am in no means suggesting this is the origin of the term but the memory popped into my head on reading the OP.
