To clarify on fronting issues, in general this only applies when a parent has the policy in their name, with a child as a named driver.
If both people on the policy are of the same age, and live at the same address, it doesn't make that much of a difference to us about who the main driver is (although we still ask the question apart from on certain types of policies).
We appreciate that lots of people have a spouse that deals with all the paperwork, etc (especially for certain ethnic groups), and so these situations do arise - in cases where it is a husband and wife/partners on the policy, and there may be convictions/claims for the named driver rather than the policyhodler, or there is a significant age difference, we rate the policy on the highest risk driver - we occasionally rate a policy on the son/daughter as well if it's an obvious case of fronting (ie 50 year old housewife, 21 year old son, Subaru Impreza on cover) - it's difficult to prove fronting enough to void the policy, so we try and charge the rlevant premium as if the 21 year old son was driving.