An employee is an individual who has entered into or works (or worked) under the terms of a contract of employment. The contract can be expressly agreed (in writing or orally) or implied by the nature of the relationship
To have employee status:
An individual must be obliged to do the work personally (rather than being able to send a substitute)
The employer needs to provide the work and the employee is obliged to accept the work
The employer needs to have some control over the way the employee does the work