"Certainly it would not be useful to inquire whether different shades of meaning are intended to be conveyed by words such as 'blatant error' used by the President in the present case, or words such as 'clearly wrong', 'plainly wrong" or, simply 'wrong', used by other judges in other cases. All these various expressions we use in order to emphasise the fault that the appellate court should only interfere when they consider that the judge of first instance has not merely preferred an imperfect solution which is different from another alternative imperfect solution which the Court of Appeal might or would have adopted, but has exceeded the generous ambit within which a reasonable disagreement is possible"