13N.I.The fixing of the seal of the commission shall be authenticated by the signature of—
(a)the Chairman; or
(b)another member authorised either generally or specially by the commission to act for that purpose; or
(c)the general manager if authorised either generally or specially by the commission to act for that purpose.
14N.I.Any contract or instrument which if made or executed by a person not being a body corporate would not be required to be under seal may, if the subject matter thereof does not exceed [F1 [F2[F3 £15,000] in value] or such larger value as the Department may by order made subject to negative resolution determine], be made or executed on behalf of the commission by any person generally or specially authorised by them to act for that purpose.