The vexed issue of so-called "mix[ed] powder" rears its ugly head from time to time, and it is clear that there will never be universal agreement as to whether it is truly fundamental to the replication of BIR cuisine or whether it is simply a short-cut or a time-saver. What is perhaps the most contentious issue, however, is why it often (but not invariably) contains curry powder, which (a) is a virtual unknown, unless the exact brand and variant is specified, and (b) contains (to a greater or lesser degree) some or all of the very same spices that make up the other parts of the recipe. Now, I was trying to bring some order into my collection of multi-terabyte drives over Christmas and the New Year, and I found on one of them a Kindle version of Paul Clay & Les Jones An Introduction to British Indian Restaurant Curries.
Browsing through it, I found their recipe for Mixed Powder (attributed to Cory Ander in the text), and was intrigued to see that they eschew "curry powder" completely, using only individual spices. I found this sufficiently interesting that I thought others might like to see this particular recipe and perhaps try it (as I shall)