Yeah, I think it's a bit out of date and I think that sub post codes can have an effect as well, but it's pretty eye opening the difference. A few years ago I played around with quotes based on my current location Vs an A rated one and I think it was the difference between 800 year and 200 year.
http://www.carinsuranceexplained.com/car-insurance-explained/car-insurance-postcode-risk-list.html
Although I think that might be out of date now.