“adult” means a person who has attained the age of 16,

F1subject to sections 14A and 15A, a reference to employment is to employment under a contract of service or apprenticeship, F2...

a reference to a contract includes a contract that is express or implied and (if it is express) whether oral or in writing,

a person is subject to immigration control if under the Immigration Act 1971 he requires leave to enter or remain in the United Kingdom, and

“prescribed” means prescribed by order of the Secretary of State.