It follows that, in the absence of any statutory indication of the weight to be given to various considerations, it is generally for the decision-maker and not the court to determine the appropriate weight to be given to the matters which are required to be taken into account in exercising the statutory power... I say 'generally' because both principle and authority indicate that in some circumstances a court may set aside an administrative decision which has failed to give adequate weight to a relevant factor of great importance, or has given excessive weight to a relevant factor of no great importance. The preferred ground on which this is done, however, is not the failure to take into account relevant considerations or the taking into account of irrelevant considerations, but that the decision is 'manifestly unreasonable'. This ground of review was considered by Lord Greene MR in Wednesbury Corporation [[1948] 1 KB 223 at 229-230], in which his Lordship said that it would only be made out if it were shown that the decision was so unreasonable that no reasonable person could have come to it. This ground is now expressed in ss 5(2)(g) and 6(2)(g) of the AD(JR) Act in these terms. The test has been embraced in both Australia and England ... However, in its application, there has been considerable diversity in the readiness with which courts have found the test to be satisfied ... But guidance may be found in the close analogy between judicial review of administrative action and appellate review of a judicial discretion. In the context of the latter, it has been held that an appellate court may review a discretionary judgment that has failed to give proper weight to a particular matter, but it will be slow to do so because a mere preference for a different result will not suffice ... So too in the context of administrative law, a court should proceed with caution when reviewing an administrative decision on the ground that it does not give proper weight to relevant factors, lest it exceed its supervisory role by reviewing the decision on its merits. (Emphasis added)