The prosecution's duty of disclosure extends to investigator's notes recording conversations between Crown witnesses and third parties that are inconsistent with the witness's later evidence, even where the witness's credibility is already substantially compromised. A failure to disclose such material constitutes a miscarriage of justice where the undisclosed material would have dealt a further serious blow to the credibility of a crucial identification witness. Where non-disclosure involves a significant denial of procedural fairness, the proviso cannot save the conviction even if the appellate court is satisfied of guilt.
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