(1) If, after the date on which an agreement referred to in section 13C(1)(b)(i) is signed by the employer and the employee (whether or not the approved flexible working arrangement to which it relates has commenced), the employer is satisfied that the flexible working arrangement would have, or is having, a substantial adverse effect on the operation of his or her business, profession or occupation, by reason of -

(a) seasonal variations in the volume of the work concerned,

(b) the unavailability of a person to carry out the duties of the employee in the employment,

(c) the nature of the duties of the employee in the employment,

(d) the number of employees in the employment,

(e) the number of employees in the employment whose periods, or parts of whose periods, of an approved flexible working arrangement will fall within the period specified in the employee's approved flexible working arrangement, or

(f) any other matters relevant to the substantial adverse effect on the operation of his or her business, profession or occupation,