I have always thought surely people could do this if they know they want to get a car that's more expensive to insure in at least a year but don't want to drive now. What it shows is that the pricing system should change...perhaps the discount should not be as much if you are taking out a policy on a car that's more expensive to insure than the previous one? Perhaps some insurance rates should come down to reflect the fact that you could have done this?
Just a thought though, if this is your plan then surely you should put your mileage estimate down as 0 on the car...is that even possible? If not, maybe put the lowest mileage you can and drive that number of miles for the sake of it!
I am a high mileage driver and have always thought that I should be earning my no-claims bonus faster...if I drive 2/3 times as far as the average driver and don't crash, surely that makes me lower risk? But then perhaps it needs to cut the other way as well...people like me are effectively subsidising people like you. I'm all for exploiting legal loopholes though as long as they don't hurt anyone.