Hello and thank you for your question. I will be very pleased to assist you. I'm a practising lawyer in England with over 10 years experience.
May I ask is your husband employed as a courier please or is this simply casual work he does from time to time ancillary to his retirement - in other words how often does he work as a courier?
From what you say he was not using your car for courier work I note.
My husband works daily as a courier as self emplyed but never uses my car. I assumed when in my car he is just a normal pensioner and in his car he is a courier.I have obviuosly misenterpred it.