3(1)A shop worker is not a protected shop worker if—
(a)on or after the commencement date, he has given his employer an opting-in notice, and
(b)after giving that notice, he has expressly agreed with his employer to do shop work on Sunday or on a particular Sunday.
(2)In this Schedule “opting-in notice” means a written notice, signed and dated by the shop worker, in which the shop worker expressly states that he wishes to work on Sunday or that he does not object to Sunday working.