An effective substitution clause will be a pointer to
self-employment. The weight of it as a pointer will vary in
accordance with the wording. In some cases it may be so unqualified
as to actually determine that there is no requirement to give
personal service at all. At the other end of the spectrum, the
evidence may suggest that the clause is almost ineffective. For
example, if the duration of a contract were very short-term, why
would it be necessary to include a substitution clause? Between the
two extremes, there will be cases where, for example, the client
must give approval. The degree to which the clause points to
self-employment will depend on the facts in each particular case
and the extent to which substitution took place.
In the case of Synaptek Ltd v Young - see ESM7260 - where the substitution provision was qualified, Mr Justice Hart indicated at paragraph 28 of his judgment that
"The Commissioners were entitled in my judgment to regard it as simply one fact among others, and, in assessing the weight to be given to it, to take into account the extent to which the provision was utilised in practice."
Further general guidance on the right of substitution can be found at ESM0530 onwards.