(1) No 1[ person] shall, after the commencement of this Act, begin to carry on any class of insurance business in 2[ India] and no insurer carrying on any class of insurance business in 2[ India] shall, after the expiry of three months from the commencement of this Act, continue to carry on any such business, unless he has obtained from the 3[ Controller] a certificate of registration 4[ for the particular class of insurance business]: 5[ Provided that in the case of an insurer who was carrying on any class of insurance business in 2[ India] at the commencement of this Act, failure to obtain a certificate of registration in accordance with the requirements of this sub- clause shall not operate to invalidate any contract of insurance entered into by him if before 6[ such date 7[ as may be fixed in this behalf by the Central Government by notification in the Official Gazette], he has obtained that certificate.]