"…, clearly there must be some material before the Commissioners on which they can base their judgment. If there is no material at all it would be impossible to form a judgment as to what tax is due"
"Clearly they [the commissioners] must perform that function [of exercising their powers in such a way that they make a value judgment on the material which is before them] honestly and bona fide. It would be a misuse of that power if the commissioners were to decide on a figure which they knew was, or thought was, in excess of the amount which could possibly be payable, and then leave it to the taxpayer to seek, on appeal, to reduce that assessment."
"…there are dangers in taking Woolf J's analysis [in Van Boeckel ] of the concept of "best judgment" out of context… the tribunal should not treat an assessment as invalid merely because it disagrees as to how the judgment should have been exercised. A much stronger finding is required; for example, that the assessment had been reached 'dishonestly or vindictively or capriciously'; or is 'spurious estimate or guess in which all elements of judgment are missing'; or is 'wholly unreasonable'. In substance those tests are indistinguishable from the familiar Wednesbury principles…Short of such a finding, there is no justification for setting aside the assessment."