Moving from Motor Trade policy to Private

In good past days I moved from private motor insurance to part-time motor trade, which allowed me to drive any vehicle - pretty handy as I always liked having several cars and selectively use either of them. To move from private to motor, my no claim bonus was accepted without any problems.

Now, that those days are gone, I'm back to one and only car, and it makes no sense to pay fairly expensive motor trade premium. But, to move to private insurance, insurance companies are not accepting my motor trade no claims bonus - meaning I would have to start from scratch again.

I'm quite furious, as this seems just another handy way for insurance companies to skim higher premium - its not that I drove different vehicles like commercials or motor bikes, my risk factor has not changed.

Anyone in a similar situation? Would any insurance company recognize no claims bonus earned on motor trade policy?