I have a mate who's parents were born in part of Kashmir. He sticks to the Baltistan theory.

Well he would now, wouldn't he? haha… Though "part of Kashmir" =/= Baltistan per se … more of an obscure cultural region related to Tibetans.

The food is made in a balti (a bowl-shaped vessel) and served in baltis (those silly little bowls), so I'm gonna say they called it after that. It's more like a gimmick made for non-South Asian Britons, to make it seem like it is something special beyond the old familiar "curry."

So far as it means something about the food's style, it seems to be specifying (at best) what might be called "wok-style" dishes. A default way to cook North Indian food is to stew it at length in a pot, but some dishes may be made quickly in a wok-like vessel usually called karaahi… but balti is an alternate name for that vessel. I could go on, but this is off topic already :)

Suffice to say, today's "balti" is similar to yesterday's "curry": British-born category that is broad and doesn't connect directly to a concept in India.