From the first case, it seems evidence of innocence wasn’t updated on the file. Looks like mistakes were made because people were too busy.
@sam that isn’t really the issue; it is just as possible that the evidence never existed in the first place (presumably there are many cases where it doesn’t). Evidence, sufficient to secure a conviction, should not exist in a case where no crime occurred, and no defence against an accusation of rape should require the defence to offer evidence that the accused is innocent.
I would expect under-resourcing in the CPS to result in a reduction in the conviction rate; there is no way in which it should result in wrongful convictions without there being a wider problem.