Technically the car is owned and operated by RSA with insurance you have not paid for. As such, you cannot pass your no claims entitlement on to them. Contact them and request they make note of your previous history. It's becoming less common that proof of no claims is requested because insurers already have the details on their database. If you lose your Motability entitlement, you can still request your claims history from RSA. As long as you can prove that you've made no claims, the new insurer should then credit your full NCB.