Thanks JJ, I admire your intent to share info with us, but you'll find this has been discussed here before and is far from clear cut, even though you may have read about it in Julian's books. No doubt some BIRs do adopt this method but it's not clear that the practice is very widespread. There's an awful lot which Julian asserts as fact which is somewhat questionable IMHO. You'll find a lot more reliable info here I would suggest, although it pays to be selective in who you listen to. Good luck 
Hey Natterjak, yeah I guessed it may have been discussed. I've not been here for a while, and just wanted to point it out incase anyone arrived from YouTube here.
I like Julian's books, it's the "closest" I've got to a takeaway dish. It doesn't mimik the high end restaurants in my area who charge ?15 for a curry! But they do taste better than the crappy places around here. So it's a step forward in improving my takeaway style curry dishes - although I still enjoy classic recipes.
I'll check out some other threads on this cooking method.