Thank you.
Our test is if there is a real possibility that the appeal courts would quash the conviction and if our case law tells us the real possibility is below the balance of probabilities—that it's less than a 50% chance in that respect. It has to be real, so it's reasonable rather than fanciful. We've got some helpful case law and decisions that guide us on that. Our court of appeal will quash a conviction if it believes that the conviction “may” be unsafe, but within the “may”, again, I think “reasonably” is implied: It's a reasonable rather than a fanciful one.
New evidence and new arguments are far and away the most common basis. Theoretically, it would be possible to quash a conviction without new evidence or argument, but it's a theoretical rather than a practical occurrence.