What is the test for reversing a judge's order?

Hence, the first question which arises is whether circumstances exist in the present case to warrant an interference by this court of the judge's order. It is clear that the second situation described by Lord Diplock is not disclosed by the circumstances here. This is not a Ward v. James situation. If we are to reverse the judge's order it will have to be because we are satisfied that he "erred in principle by giving weight to something which he ought not to have taken into account or by failing to give weight to something which he ought to take in account". In my respectful view, for the reasons I will now outline, he erred on both counts but primarily on the second.