I gave Kris Dhillon's curry sauce recipe to my "old man" and, embarrassingly, he used a bit of lateral thinking and risk taking to create a bloody good curry sauce.
Basically he added a whole jar of Sharwoods Madras Curry Paste (290g) to the tomatoes.
The result is better than I could have imagined and *almost* captures, spot on, the elusive restaurant taste. I say almost because the end result is a little too salty and too heavily spiced - perhaps 1/2 a jar or 3/4 a jar would produce a better result. But the elusive taste, which I identify as being heavily corriander inspired, is there.
Gareth.