I'm not sure we're on the same page here, and I know nothing of Jamie Oliver's curries, but just for clarity, the general idea of BIR curries here is that you pre-prepare a base gravy which, along with the oil, is used as a carrier for the different spices, herbs and other ingredients demanded by a specific recipe.
So you might use the same base gravy to make a range of different curries from Kormas to Vindaloos. The base remains the same, but the other ingredients vary in type and quantity.
Mostly, a lot of the ingredients will be pre-prepared - the base gravy, the spice mix, the meat, the vegetables, the rice etc. In this way, a full-blown individual curry can be plated up in less than 10 minutes from start to finish.
Sorry if you already have a good grasp of the BIR cooking method, but I thought I'd better add this info just in case. Happy currying!
