Police and Criminal Evidence Act 1984

3 Where in any proceedings a statement based on information supplied by any person is given in evidence by virtue of section 68 above—

(a) any evidence which, if that person had been called as a witness, would have been admissible as relevant to his credibility as a witness shall be admissible for that purpose in those proceedings ;

(b) evidence may, with the leave of the court, be given of any matter which, if that person had been called as a witness, could have been put to him in cross-examination as relevant to his credibility as a witness but of which evidence could not have been adduced by the cross-examining party ; and

(c) evidence tending to prove that that person, whether before or after supplying the information, made a statement (whether oral or not) which is inconsistent with it shall be admissible for the purpose of showing that he has contradicted himself.