33.—(1) An employer shall not employ an employee to do any work in a relevant period during which the employee has done work for another employer, except where the aggregate of the periods for which such an employee does work for each of such employers respectively in that relevant period does not exceed the period for which that employee could, lawfully under this F31[Act or the Activities of Doctors in Training Regulations], be employed to do work for one employer in that relevant period.

(2) In subsection (1) “relevant period” means a period of—

(a) 24 hours,

(b) 7 days, or

(c) 12 months.

(3) Whenever an employer employs an employee in contravention of subsection (1), the employer and the employee shall each be guilty of an offence.

(4) Where an employer is prosecuted for an offence under this section it shall be a good defence for him or her to prove—

(a) that he or she neither knew nor could by reasonable enquiry have known that the employee concerned had done work for any other employer in the period of 24 hours, 7 days or 12 months, as the case may be, in respect of which the prosecution is brought, or

(b) that he or she neither knew nor could by reasonable enquiry have known that the aggregate of the periods for which the employee concerned did work in the said period of 24 hours, 7 days or 12 months, as the case may be, exceeded the period for which he or she could lawfully be employed to do work for one employer in the said period of 24 hours, 7 days or 12 months, as the case may be.