This thread here on CRO has it all from when I made it, including the recipe I used.  OP by Dal Puri and a very easy / simplified recipe posted by Chewy Tikka. 

https://curry-recipes.co.uk/curry/index.php?topic=11509.0#google_vignette

Unfortunately, the link within to the Australian site I used is broken (Spicemama.com.au)  However, I think it was only a link to the sale of her product (Wayback Machine).  Here is the link to her Blog site which contains some recipes using it in the Recipe section.
https://www.spicemama.au/

I found the concept and production of BBM intriguing. I made the best possible copy I could.  I very much enjoyed it and the dishes made using it. I gave a bottle to my dad and when it was all gone, never revisited.

They probably use a very bland base gravy (or several different ones) and rely heavily on variation of the spices and other ingredients that go into the pan at first stage.  I have experienced your problem myself with the BIR method, even though it makes excellent curry.  If I make a particular base gravy and mixed powder as specified by a grouped list of recipes, and use them for 10 different dishes, they will all have the same undertone of flavour.  This is unavoidable really.  I specifically like to make "weak" base gravy, when I'm making mild curries.   If you don't, they will taste the same.  I make mixed powder, but I'm finding that I use less and less of it, when it gets down to making the variation of dishes I want.

I currently have 3 different Mixed Powders in my spice cupboard, 4 or 5 different curry powders from a packet and 4 or 5 different types of chilli powder.  I have just found the delight of Deghi Mirch, although I've known about it for years and had the unopened pack in my reserve box for quite a while.  If you want things to taste different, you have to mix it up.

Hotel style uses up to 7 different gravies, alone and in combination, but that isn't the BIR method.  Base gravy, mixed powder, a few different spices and pre-cooked chicken (or lamb).  Chilli heat is the major variation that occurs in some lines and then you have the 3 types you've outlined.

The thing is that the local T/A is counting on not too many people coming back too regularly and, if they only go back every second week and have a favourite dish, they're going to be happy every time.  This is especially applicable to people who have never tried to cook for themselves.

Excellent stuff Unclefrank.  For the Butter Chicken last night, I had made a simple and basic Makhani Gravy and did the Taz base method stage 1 reduction thing using very diluted base to get the dish going.  I then added the Tikka Chicken and Makhani and finished off with a splash of extra cream.  It turned out pretty good.  I'll give your 2 recipes a go for sure.  I really enjoyed all 3 dishes I made using the Taz base and it has a lot of depth from that initial reduction and cooking the spices that way.  My Makhani Gravy included a paste of cashews and char magaz.

I'd really appreciate your take on a CTM.  I'm going to give the Cook4one Balti Passanda a try with my pre-cooked lamb and Taz Base tonight.

The chicken tikka pre-cook could be a game changer for me. It certainly tasted pretty good straight out of the pot.  I will need to use less water next time as Ì was unable to get to the nearly dry point.  It has been observed here that our chicken breast is possibly being pumped full of water.  I know that when I try to fry some it tends to release a lot of water which bubbles away before browning begins.  I cooked some chicken breast a few months back and weighed it to find there was a 30% loss.