(3)Where a certificate of insurance [* * *] [The words 'or cover note' were omitted the Motor Vehicles (Amendment) Act, 1956 (100 of 1956), section 76 (w.e.f. 16.2.1957).] has been issued under sub-section (4) of section 95 to the person by whom a policy has been effected, so much of the policy as purports to restrict the insurance of the persons insured thereby by reference to any conditions other than those in clause (b) of sub-section (2) shall, as respects such liabilities as are required to be covered by a policy under clause (b) of sub-section (1) of section 95, be of no effect:Provided that any sum paid by the insurer in or towards the discharge of any liability of any person which is covered by the policy by virtue only of this sub-section shall be recoverable by the insurer from that person.