It’s a tiny, but growing sector. Most UK “Indian” restaurants are owned by Bangladeshis and tend to be generic Anglicised “curry houses”. I often describe them as “any protein with any sauce” places that start with a base sauce to which more chilli might be applied. So, you might have a vindaloo that is offered as chicken, prawn, lamb or vegetable - rather than the usual pork in Goa. Or a rogan josh that has the same various proteins, rather than just the traditional lamb. The growing market is for restaurants owned by Indians (and, to
a lesser extent, Pakistanis) serving more traditional regional food. All four places that I go to with some regularity are like this - and, of course, all the better for it.