So have I, and you are quite right of course. In fact the word curry, simply means gravy in India. I know of no other dishes that were specifically known to be invented in Birmingham though, other than the most popular 'Indian' dish of all, the Tikka Mosalla.
Yes l know what you mean. For me the best barometer is to try their Onion Bhaji, a stock dish of which most curry houses must sell a great many. If the Onion Bhaji starter is good, then so most probably will your main course be.
First created in Birmingham, how authentic!, but l agree, if you like it then you like it.
As for me, l can't make my mind up, it's either a Chicken Danshak, or a Chicken Patia, but always served with Lemon Rice and a Brinjal Bhaji. Curry house of choice is the Akash in Horsham.