Thanks for your help CA.  I've been trying to get that BIR taste for a few years now and I honestly think that I've cracked it.  I think the key is cooking your base sauce and tomato paste until nice and dark, and using lots of oil.  That's it!

Made it, it was very good.  I only ate a bit of it and had the leftovers the next day.  I truly believe the theory about not cooking the curry yourself giving the "taste" as I enjoyed it more the next day.

Only problem I had was that a bit of water seperated from the curry when finished.  Any ideas for that?  I don't want to cook the crap out of the meat to reduce the water content so I think I will try adding the base gravy bit by bit so each addition has more time to reduce.

Tonight I am going to make your Vindaloo with Darth's base.  I will let you know how it turns out!