Guide to determining status: the obligation/right to send a substitute must be genuine
In any case where substitution is at issue, it is particularly important to bear in mind that the obligation to provide a substitute must be genuine. Always consider whether the obligation is genuine where other factors (for example, membership of the employer’s pension scheme, payment of sick pay, etc) or a dispassionate consideration of the engager’s requirements and the nature of the work simply do not fit with such an obligation.
Similar considerations apply where there is a right, not an obligation, to send a substitute. However, the weight to be given to such a right will depend on the particular facts of eachcase.
Where the worker may only suggest a substitute, there is of course no right to send a substitute. As Park J. said in his judgment in the case of Usetech Ltd v Young  EWHC 2248 (Ch) –
‘Of course if, in the events that happened he became unable to provide his services under the assumed direct contract between himself and ABB (for example because of illness), he might have drawn on his contacts to suggest to ABB a possible replacement for himself. Mr Hunter of ABB said that the company would have given some weight to Mr Hood’s suggestion. That however is a far cry from the direct contract between Mr Hood and ABB containing an express provision which conferred on him an entitlement to substitute someone else for himself, subject only to the substitute having the required skills.’This factor does not necessarily work the other way. Where a worker has to undertake the work personally that does not mean the worker must be an employee. There are many examples (for example, in the professional field) where self-employed individuals have to undertake the work they have agreed themselves. The lack of a right to provide a substitute may be a pointer to employment but it is certainly not conclusive on its own.