None of whom seem to be outraged over the fact that the jury had very little idea that the witnesses could have changed their story, after having contact with the Evans family. But the appeal court knew it! It was the entire basis for the appeal in first place
Changed their story implies their initial story was different to their final statement. It wasn't. However, their initial statements were much less detailed. They did not answer questions they weren't asked. Without seeing a full transcript of the trial I don't know what questions the prosecution asked but they were certainly entitled to put any differences between the witnesses final statements and their original statements to them. They will have done everything they can to discredit the new witnesses. However, the fact that there was independent corroboration of at least some of their evidence and the apparent inability of the victim to deny the remainder may have been enough to persuade the jury that these witnesses were sufficiently credible to cast reasonable doubt on the conviction.
they are bound by the law and don't have limitless resources
No they don't but they have far more resources than any defendant. It is very unusual for the defence to be able to outspend the prosecution (CPS and police) in a high profile case.
but statements to the police shortly after the actual events ate surely evidence
Only if one side chooses to put them into evidence. Unless the prosecution or the defence put McDonald's initial statement into evidence the jury is not entitled to see it.
Why no conspiracy charges - it all must have been planned
Because there is no evidence of planning. And without a rape conviction there can be no conspiracy conviction.
And then when they found out that they WERE in the public domain, they allowed it anyway
The same rules apply to the Court of Appeal. They must make their decision based on the evidence presented by the prosecution and the defence. When the information about what was in the public domain became available they invited both sides to make further submissions. Neither side made any submissions. The Court of Appeal therefore has to ignore this information. Note that the Court of Appeal did not have to decide whether or not they believed the new witnesses, just whether or not their evidence was capable of belief. It was up to the jury to decide whether or not to accept their evidence.
Mightymouse - My apologies. I had forgotten that there is a very rarely used provision of the relevant law that allows evidence of the victim's sexual history as evidence of consent if the description of the previous encounters is so similar to the description given by the alleged rapist that it is unlikely to be coincidence.
it seems that it's not illegal (though it should be)
Why? Prosecuting authorities frequently offer rewards for information leading to conviction. Why should it be illegal for the defence to do the same? The jury certainly need to know if witnesses are being paid and particularly if payment is dependent on the verdict. In this case both the new witnesses denied that they have received any payment or will do so in future. If that turns out to be false they could face prosecution for perjury.