“76. Once this is recognised, it can immediately be seen that it would be inconsistent with the purpose of this legislation to treat the terms of a written contract as the starting point in determining whether an individual falls within the definition of a “worker”
“If a contractual right, as for example a right to substitute, exists, it does not matter that it is not used. It does not follow from the fact that a term is not enforced that such a term is not part of the agreement.”