I guess insurance is one of those mysterious variables in life, whether you do good (stay claim free) or bad (make a fault claim) the results can still come back with an increased premium due to market changes and stats.
I'm pretty sure that if I was to get a quote for my Supra with 0 ncd and then another with my 7 years ncd, then the difference between both quotes would not be equal to the amount of discount I had accumulated let's say 50%.
The only thing I would like to say about our club insurers is that they will talk you through your price and give reasons for their decision, if they can't match it then they will tell you, and to me that saves me waiting around for another 2 hours while a company gets back to me with a slightly better but not good enough quote.
Shop around I guess is the moral of the story :-)