Well this past weekend I tried to do a proper BIR curry and failed spectacularly.

First all, the base. I used CT's Three Hour Base as I don't have a pressure cooker
https://curry-recipes.co.uk/curry/index.php/topic,5635.0.html.
Here's were it started off wrong. I didn't use nearly enough oil. After cooking and sieving and reducing further the base never split. What I was left with was a very thick, and very sweet base with an almost roux-like quality. This was on Friday.
Sunday, I then proceeded to try and make a chicken vindaloo with the base. I had no problem tempering my spices, cooking the chicken and then adding my base, but remember there wasn't enough oil in the base, so again the sauce would not split. The result was a rather bland and flavourless vindaloo that didn't have that certain BIR quality.
To make matters worse the missus and I went for curry Saturday night and we ate the leftovers with my attempted vindaloo. Night and day.
I'm not discouraged to try again. I know the faults were my own and not the recipe's. I just wanted to share my rather dismal start to really understanding BIR curries.