OK, I chatted to the guy again tonight and have his recipe for making up his standard sized pot of base sauce
He was at great pains to be wary of adding too much chilli, salt and garam masala. Too much of any of these will ruin the base and are irreversible.
Now what I find particularly interesting is the use of garam masala
This spice mix has black cardamom in
That is the spice I felt was missing from the Kris Dhillon recipe.
When chatting to chefs, about a missing "taste", black cardamom was mentioned twice.
Perhaps it is considered as the most important spice for the base
In isolation it has a foul smell, almost medicinal
But the curry gravy I froze, leaving them in, had this warm flavour when thawed out.
Nothing like it's original character
If you sifted out the pods they were the source
Totally changed
If left in, for any length of time, you really don't need much
If the curry houses are keeping their base for three days, then this spice's effect would really evolve