If I was served a Pataks curry in an Indian restaurant I would walk out.
They might serve that shite in weatherspoons and the like but no decent Indian takeaway/restaurant would.
I don't think any serious curry restaurant would serve some diced chicken breast in a half jar of Patak's sauce, or at least I'd be surprised if they did.
What most curry restaurants actually do is prepare a vat of 'base sauce' out of onions, other vegetables, ghee or oil, and spices to their own recipe. When someone orders a particular dish they take some base sauce and turn it into the madras or korma or dhansak by adding more spice as well as tomatoes, coconut milk, or whatever, and add the chicken or lamb or whatever. For both speed and consistency these final adjustment spices are generally pastes and Patak's has absolutely nailed this market within the trade.
So, no two restaurant's chicken madras tastes exactly the same because the base sauce will have been prepared and then augmented differently, even if the 'madras' effect is actually courtesy of a Patak's five litre catering bucket. For the same reason it won't taste the same as what you cook from a Patak's sauce jar at home. It also explains why a dish that should take an hour or two of cooking is on your table within 25 minutes.