As already said, it isn't just cheaper to insure an older and/or slower car as often viewed as higher risk if you drive a shitter over a brand new 'pride and joy' car. Added to the fact that vehicle secuity has (well supposed to) increased then insurance prices are all over the place.
I'm looking at getting a dedicated classic policy for my saff instead of just having it on my trader policy and was pleasantly surprised with the £175 quote yesterday!