13Where in any proceedings a statement contained in a document is admissible in evidence by virtue of section 68 above or in accordance with section 69 above it may be proved—
(a)by the production of that document; or
(b)(whether or not that document is still in existence) by the production of a copy of that document, or of the material part of it,
authenticated in such manner as the court may approve.
14For the purpose of deciding whether or not a statement is so admissible the court may draw any reasonable inference—
(a)from the circumstances in which the statement was made or otherwise came into being ; or
(b)from any other circumstances, including the form and contents of the document in which the statement is contained.
15Provision may be made by rules of court for supplementing the provisions of section 68 or 69 above or this Schedule.