In actual fact very few companies will accept no claims bonus proof from a motor trade policy.
I would recommend you try gettinga quote from the same company that insured the motor trade policy, or try a broker oryou can try brokers. HOWEVER it is very important you tell them and get them to accept (Take a note of the persons name and date / time) that it is motor trade no claims bonus.
Huckster ask at your work if they will accept no claims bonus from a motor trade policy, you may get a surprise