Depends on what the trade is. The vehicle on the trade policy needs to be in use as part of the course of its business, so if it's a sales vehicle - the answer is no. If you're lending a vehicle that is in general use, like a van, yes. This is because it would only cover them to drive in connection with their business. The vehicle has to be on the Motor Insurers database for you to use it on an extension of use through your policy. Check on there. If it is on, then you can. If it isn't, you cannot.