s 27 Proof of statements contained in documents.
Where a statement contained in a document is admissible as evidence in criminal proceedings, 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; and it is immaterial for the purposes of this subsection how many removes there are between a copy and the original. . . . .