I haven't read the thread, so apologies if I'm repeating, but this is what dh and I have done (on the insurance company's advice).
I have always been the car-owner and insurer, although dh has at times had a company car. I have maximum NCD, but dh of course has none. So last year we inusred the car in my name, as usual, with dh as a named driver, but this year we insured it in his name with me as a named driver. Because of some way in which the insurers consider married couples, dh gets the benefit of my NCD. Once you have a full NCD you can carry it forwards for one un-insured year, so each year we will swop over on the car's insurance, and that way we will both have a maximum NCD without dh having to build one up or pay for an additional policy. It does mean that we loose out on the renewal discount because each year we effectively take out a new policy, but that's peanuts compared to what it would cost to insure dh separately.
HTH