Include him as "named driver". But be aware that the main driver must still be the policyholder and that the company may seek to specify the max. miles driven by him. They will check in the event of a claim whilst he was driving.
I went on my parents insurance when I first passed...although that was 6 years ago and direct line were the only people that would insure me on their insurance and it cost �40 extra a month to have me on it so I'd recommed them....still with them and now pay only �20 extra per month to be on it
When I was 17, My mum was the named driver on the Saxo (1.4) we had, my dad an additional driver and so was I.
When I passed my test (still 17) I was still an additional driver and now at 18, my insurance on a 1.2 Corsa is still the same. I'm with Direct Line plus I recently just sat my Pass Plus course.