D Gibbs,
There are three ways to approach this:
The first one is to add your son as a named driver under your own policy but you don't want that because it will affect your no claims bonus if a claim is made by your son.
The second one is to get your son his own car insurance policy but because he just have a provisional licence, it may be difficult to find especially for the car you're trying to get him insured on. This is also a yearly policy which means that the quote may be inflated because he's still a learner driver.
The third one is to get
learner drivers insurance from
Collingwood. You can get him insured for 4 weeks initially so that he can get the practice he needs in your car and if you need more cover then you can extend it a week at a time. The policy will be under his name which means that your insurance will not be affected in any way and when your son passes his driving test, then he can shop around for better car insurance deals.