Which principle will NOT allow Jack's car to be insured by his neighbour?

The principle that is relevant to the situation described is insurable interest. Insurable interest refers to the requirement that the policyholder must have a legitimate interest in the insured item; in this case, Jack must have a vested interest in his car to insure it. Because the insurance contract is a safeguard against loss, the person taking out the insurance (the neighbour, in this case) must stand to suffer financial loss if the car were damaged or destroyed.

In this scenario, the neighbour does not own the car and, thus, does not have insurable interest in it. Therefore, the insurance provider would refuse coverage because the neighbour would not suffer any direct financial loss from a claim related to Jack's vehicle.

The other principles mentioned—contribution, indemnity, and subrogation—are related to the handling of insurance claims, compensation, and the rights of insurers after claims are paid, but they do not affect the foundational requirement of having an insurable interest in the property being insured.