16The application of the seal of a funding authority shall be authenticated by the signature—
(a)of the chairman or of some other person authorised either generally or specifically by the authority to act for that purpose, and
(b)of one other member.
17Any document purporting to be an instrument made or issued by or on behalf of a funding authority and to be—
(a)duly executed under their seal, or
(b)signed or executed by a person authorised by the authority to act in that behalf,
shall be received in evidence and be treated, without further proof, as being so made or issued unless the contrary is shown.