Read 100 Best Balti Curries now. Get the distinct impression the restaurants mentioned (and there are a lot) have given absolutely nothing away recipe-wise on their base gravies, mix powders, and gm. Instead, the authors have come up with generic mixes out of thin air, and every recipe in the book seems to refer back to these. Still, good book for 1 p plus postage, and there are plenty of ideas; some of the starters look authentic too.
Rob

Balti Towers in Halesowen are mentioned in the book. Home delivery range for me. Just had a TA from them. Unbelievably (really) bad. It's gone in the bin! When I calm down I will post a short review in the appropriate section.