All noted, i know its no big deal, however over the past 20 years ive got most of the books of how to cook bir's curries at home. kris dillion, pat chapman, the curry secret, the balti selection to name a few, non of them really come close to the taste, if you trawl the internet like i do i found no end of new websites all offering more or less the same recipes over and over again, tried them non of them again replicate the bir taste, its called jumping on the band wagon for publicity, promoting there product/business and so called knowledge, i'll stick by my guns! if the books/videos held the true secrets then forums like this wouldnt exist. i shall still bash my pan and share my bases with all, We will take victory ;D
Good on you!
It sounds very much like my own quest for the BIR taste, which began in earnest back in 1980-ish. (I too have all those books you mention, and more, as I reckon do many other forumites here.)
Quests for the BIR taste are highly individual, and are based on many disparate factors, and it's really difficult to appreciate or understand exactly what you or anyone else is searching for and trying to achieve (without meeting up and going for a BIR in your area that produces the taste you're after, of course). For what it's worth, for me, the taste I've been chasing I discovered in Glasgow in the early 80s (1981). Trying to explain it is impossible, but I know exactly what it is I'm after, in the same way that you know exactly what it is you're seeking.
The thing is, I don't come on this forum in search of the BIR taste any more, or in search of any 'secret'. In my humble opinion, I've been able to recreate BIR quality (or even, at times if I dare say it, better) at home for a good while (even, on occasion, to the standards of my holy grail of Glasgow circa 1981), and all my research has led me to the inescapable fact that there is almost certainly no 'secret'. Instead, I think that the difference between a great, good and indifferent curry is down to the skills of the chef - not some elusive, mythical missing secret ingredient or magic base.
While I'm more than happy with my BIR cookery results at home, I will say that there is NO WAY I'll ever be able to match the finest exponents of the art. I've been blown away by some BIR chefs and the amazingly intense, deep and flavoursome curries they can produce, but this is down to their skill and knowledge, not a 'secret' ingredient.
But that's just my take on it, and there's no saying that it's the right one.
Unfortunately, these super skilled and knowledgeable chefs are few and far between these days...
Anyway, whatever the taste you're striving for, I wish all the very best and hope you find it - and of course share it with all of us here!