s 127 Expert evidence: preparatory work.
(1) This section applies if— (a) a statement has been prepared for the purposes of criminal proceedings, (b) the person who prepared the statement had or may reasonably be supposed to have had personal knowledge of the matters stated, (c) notice is given under the appropriate rules that another person (the expert) will in evidence given in the proceedings orally or under section 9 of the Criminal Justice Act 1967 (c. 80) base an opinion or inference on the statement, and (d) the notice gives the name of the person who prepared the statement and the nature of the matters stated. (2) In evidence given in the proceedings the expert may base an opinion or inference on the statement. (3) If evidence based on the statement is given under subsection (2) the statement is to be treated as evidence of what it states. (4) This section does not apply if the court, on an application by a party to the proceedings, orders that it is not in the interests of justice that it should apply. (5) The matters to be considered by the court in deciding whether to make an order under subsection (4) include— (a) the expense of calling as a witness the person who prepared the statement; (b) whether relevant evidence could be given by that person which could not be given by the expert; (c) whether that person can reasonably be expected to remember the matters stated well enough to give oral evidence of them. (6) Subsections (1) to (5) apply to a statement prepared for the purposes of a criminal investigation as they apply to a statement prepared for the purposes of criminal proceedings, and in such a case references to the proceedings are to criminal proceedings arising from the investigation. (7) The appropriate rules are Criminal Procedure Rules made by virtue of — (a) . . . section 81 of the Police and Criminal Evidence Act 1984 (advance notice of expert evidence in Crown Court), or (b) . . . section 20(3) of the Criminal Procedure and Investigations Act 1996 (c. 25) (advance notice of expert evidence in magistrates' courts).