there is a lot of confusion over the issue of whether a vehicle needs to be separately insured if someone who is not the owner or hirer under an HP agreement is driving it pursuant to a driver extension on their policy.

The answer is it doesn't. Section 143 RTA 1988 requires the person using the vehicle on a highway to be insured. It does not require the owner or keeper to also have insurance at the same time.

Basically, whoever's driving it must be insured to do so.