"It is of fundamental importance to the understanding of these proceedings to keep firmly in mind that this court, and the appeal tribunal, only have power to set aside a decision of an industrial tribunal if it is shown that in reaching its decision the industrial tribunal have erred in law. If the issue is only one of fact, this court has no power simply to substitute its own interpretation of the facts for that of the industrial tribunal. This is to a lawyer established law, but it is worth re-stating yet again, because many who are not lawyers find it difficult to grasp the concept of the limited function of the court, and therefore have difficulty in understanding decisions of the court.