(1) If, after a certificate of insurance 2[ has been issued under sub- section (4) of section 95 in favour of the person by whom judgments against persons insured in respect of third party risks. a policy has been effected, judgment in respect of any such liability as is required to be covered by a policy under clause (b) of sub- section (1) of section 95 (being a liability covered by the terms of the policy) is obtained against any person insured by the policy, then, notwithstanding that the insurer may be entitled to avoid or cancel or may have avoided or cancelled the policy, the insurer shall, subject to the provisions of this section, pay to the person entitled to the benefit of the decree any sum not exceeding the sum assured payable thereunder, as if he were the judgment debtor, in respect of the liability, together with any amount payable in respect of costs and any sum payable in respect of interest on that sum by virtue of any enactment relating to interest on judgments.