A notice, order, consent, demand or other document that a local authority are authorised or required by or under this Act to give, make or issue may be signed on behalf of the authority—
by the proper officer of the authority or the district surveyor, as respects documents relating to matters within his province, or
by an officer of the authority authorised by them in writing to sign documents of the particular kind or, as the case may be, the particular document.
A document purporting to bear the signature of an officer—
expressed to hold an office by virtue of which he is under this section empowered to sign such a document, or
expressed to be authorised by the local authority to sign such a document or the particular document,
is deemed, for the purposes of this Act and of any building regulations and orders made under it, to have been duly given, made or issued by authority of the local authority, until the contrary is proved.
In subsection (2) above, "signature" includes a facsimile of a signature by whatever process reproduced.