I had heard that it does - but on experimenting on 'confused.com' - the results are mixed.
Having the car in my lads name, and the insurance in his name - as a provisional driver it seems to make no difference - strangely, I could now get him insured for £332, which beats Admiral by around £200 (they were the cheapest when I went through this exercise a couple of months ago).
Once he's passed his test, I can still get insurance for him only for just over £900 or so - but that's with a company I haven't heard of (they don't have a defaqto rating) - Collingwood, the same company that are the cheapest under the provisional searches too.
If I have myself on as a named driver, Collingwood disappear from the running, and Tesco come in at the same price (£900-ish) - but Tesco, without me on are over £1250.
So, in short, worth experimenting. Certainly, as my lad will be at home for a couple of years yet, it makes sense to have the car available for anyone to jump in it without worrying, so we'd always be on as named drivers - quite handy when the other cars are in for servicing etc. There's no public transport around here - and it's nearly a two hour walk to town!
Just be aware that if he's driving it the most, he needs to be the named driver, because otherwise that is fronting =)
I know what you mean, he will be the primary driver - all others, Mum & Me, will be named as additional drivers. This way he accumulates his own NCB too.