As to every contract of insurance made between an insurer and any insured by which such insured is insured against loss or damage on account of the bodily injury or death by accident of any person for which loss or damage such insured is responsible, whenever a loss occurs on account of a casualty covered by such contract of insurance, the liability of the insurer shall become absolute and the payment of the loss shall not depend upon the satisfaction by the insured of a final judgment against him for loss, or damage, or death occasioned by the casualty. No such contract of insurance shall be cancelled or annulled by any agreement between the insurer and the insured after the insured has become responsible for such loss or damage, and any such cancellation or annulment shall be void.