“A more nuanced approach in modern public law is to test the decision-maker’s ultimate conclusion against the evidence before it and to ask whether the conclusion can (with due deference and with respect to the panel’s expertise) be safely justified on the basis of that evidence, particularly in a context where anxious scrutiny needs to be applied.”
“ there must have been a mistake as to an existing fact, including a mistake as to the availability of evidence on a particular matter; the fact or evidence must have been "established", in the sense that it was uncontentious and objectively verifiable; the appellant (or his advisors) must not have been responsible for the mistake; and the mistake must have played a material (though not necessarily decisive) part in the tribunal's reasoning.”