‘It seems to me that the ‘statutory condition’… which the Tribunal has to determine in an appeal… is whether it appeared to the Commissioners requisite to require security. In examining whether that statutory condition is satisfied the tribunal will… consider whether the commissioners had acted in a way in which no reasonable panel of Commissioners could have acted or whether they had taken into account some irrelevant matter or had disregarded something to which they should have given weight. The tribunal may also have to consider whether the commissioners have erred on a point of law [[1995] STC 941 at 952]’