Thanks for your reply Dopiazafurther details ADVB. 

I have tried numerous stocks in the past (including off-the-shelf liquid stocks, stock cubes and granules, "akhni stock" and home made stock of chicken, vegetables and meat) but I will retry adding chicken stock, as you describe.

I am determined to find (what I feel must be) that missing ingredient from the curry base!

CA - I'm new on here. I've read a lot of these posts and used the Taz base last night for the Taz Dopiaza
I've been cooking decent food for 20 years at home and think less is more. A base is mostly water, tap water.
if you drank this then immediately tasted filtered water the taste difference is unbelievable after removing
the crap from it. I used filtered water in my base and although no comparison to make, it was bob on. The finished dish
needed sugar and salt to balace along with fresh lemon juice which brings everything together.

Hope this helps.