Suppose Jane accuses Alf. Bill tells Constable Dann he heard Jane admit she made it up.
If the Constable makes a note of what Bill said, the note must be disclosed to Alf. The note is “a thing… that would tend to help the case for the accused” (s.590AB(2)(b)).
But what if the information is only in the officer’s head? Is it a “thing” to which the obligation to disclose attaches?
Yesterday, the Court of Appeal decided that even raw knowledge must be disclosed:
“a prosecuting authority’s duty of disclosure of relevant information and evidence is not just a protection against miscarriages of justice. Its fulfilment is a presupposition of a fair trial.” at 
“…, the police officer’s attention was only upon facts that might assist the prosecution case…. He was uninterested in learning that there may be issues about the reliability of the complainant and so he ignored (or did not hear) what Ms V had to say. He made some desultory, sparse and useless notes of his conversation with her but failed to record any of the highly important things that Ms V was earnestly attempting to convey to him.” at