"I must now consider what is meant by a contract of service.
"13. In the event that the contractor provides a relief driver, the contractor must satisfy the company that such a relief driver is trained and is suitable to undertake the services."
"On the odd occasions, such as the night before the tribunal hearing, he has simply had a day off and provided a substitute. There might come a point at which the provision of a substitute is so frequent as to change the whole nature of the arrangement but there is no evidence before me that that point has been approached in any degree at all."