ESM0516 - Guide to determining status: control - overview
In the 1950s the courts took the view that the distinction between employment and self-employment turned on who controlled the worker when carrying out his or her duties. If the engager had the right of control then there was employment. Since then there has been a lot of case law where control has been a feature, notably Ready Mixed Concrete (South East) Ltd v Minister of Pensions and National Insurance  2QB497, which have reaffirmed that the presence of control is an essential and necessary consideration in determining whether a contract of employment exists. Although the right of control is a significant factor and one which must be present in establishing whether someone is self-employed or employed, that right is not conclusive on its own. It has to be considered in the light of all the other factors relevant to employment status (see ESM0515).
What we are concerned with is the right to control what the worker has to do, where it has to be done, when it has to be done and how it has to be done. It is the right to exert control that is significant; not whether that right is exercised (see ESM0518). In practice, the employer may rarely (or never) exercise this right; particularly where the worker is a skilled individual used to working on his or her own initiative (see ESM0527). It can be difficult to demonstrate both that a right exists and that there is actual control. The engager may not be able to exercise control over all aspects of the work. If so, this does not necessarily mean that there cannot be employment although the greater the level of control there is, the stronger the pointer towards employment. You must also bear in mind that the right of control is only one factor to take into account and must be considered in context. The right of an engager to exert control over a worker is a strong pointer towards employment.
When investigating the status of a worker you need to establish whether the engager has the right to control the worker. The fact that the right exists carries a lot of weight even where little control is exercised. For example, a manager may not closely supervise the work of an experienced or skilled worker, although the right exists.
Control is a necessary condition of a contract of employment so to satisfy the test laid down by MacKenna J in the Ready Mixed Concrete case - see ESM7030 - there must be evidence to show a “sufficient degree of control” over the worker exists.
The Court of Appeal case Autoclenz Ltd and Belcher & Ors  EWCA Civ 1046 provides very useful guidance as to what the Courts should accept as to the level of control necessary to satisfy the test laid down in Ready Mixed Concrete - see ESM7310.
Where the engager has no right of control whatsoever over the worker, there will not be a contract of service. In general, the more control that exists the more likely it is that the relationship between the engager and the worker is that of employment.