This is a typical example of fronting on car insurance - putting an experienced driver (having considerable no claims bonus) as the main driver to bring the premiums down. It is illegal and insurers have become very strict about this now. If you go down this route, you'll find that your car insurance policy will be void when you make a claim.
There is no law to say that the policyholder should be the registered keeper. However you will find it really difficult to get car insurance if the policy holder/main driver is not the actual registered keeper. There are only a handful of companies which will accept that and they're changing the rules as well.
