Old style BIR still run by Mitu Chowdhury (20+ years and still going strong). He's been done at least twice for using illegal immigrant chefs but don't take that as a bad thing, imho it's a strong indicator of good BIR food.

Still apparently using the old recipes as I enjoyed a lovely oily vindaloo with "the taste (tm)" tonight. Pilau rice was competent but the meat vindaloo was highly enjoyable. Three pieces of potato which seemed a bit cost-cutty but that's splitting hairs. The sauce was glorious.

They are indeed schooled in traditional cooking. However they are, crucially,
cheap, meaning BIRs who employ the illegals don't tend to skimp on the pre-cooks in the way that those who are having to pay minimum wage have to. The result is far better flavours in those places which use the cheap immigrant labour (as can be seen from the ongoing disappearance of "the taste" as more places lose their illegal chefs).

Within easy travelling distance; I wonder which is their quiet night .....
** Phil.