As fars as I know, they only need to be owned by a business to be commercial. As the legislation doesn't define commercial vehicle as needing any specific registration or vehicle type.
On a side note. The person who registers the vehicle (registered name) is not necesarily the vehicle owner. Parents buy and own a vehicle but the child is responsible for the running costs of the vehicle. The child can register the vehicle (in their name) but not own it.
A person can own a business and a vehicle. Register the vehicle in their name but claim it to be a commercial vehicle.
Happy Days.

