17(1)For a purpose other than is mentioned in sub-paragraph (2) below, a document is validly executed by an authority if signed on behalf of that authority by their chief executive, or by another of their members, or by a person authorised to sign the document on their behalf.
(2)For the purposes of any enactment or rule of law relating to the authentication of documents, a document is validly executed by an authority if subscribed on behalf of the authority by being executed in accordance with the provisions of sub-paragraph (1) above.
(3)A document which bears to have been executed by an authority in accordance with sub-paragraph (2) above shall, in relation to such execution, be a probative document if—
(a)the subscription of the document bears to have been attested by at least one witness; or
(b)the document bears to be sealed with the seal of the authority.