If any letters of administration granted to the Administrator-General in accordance with the provisions of this Act are revoked, upon the grant of probate of a will, or upon the grant of letters of administration with a copy of the will annexed, all payments made or acts done by or under the authority of the Administrator-General in pursuance of such letters of administration, prior to the revocation, which would have been valid under any letters of administration lawfully granted to him with a copy of such will annexed, shall be deemed valid notwithstanding such revocation.