(1) Where an employer has reasonable grounds for believing that an employee of his or hers who is on paternity leave is not using the leave for the purpose specified in section 6(1), the employer may, by notice in writing given to the employee, terminate the leave and the notice shall contain a statement in summary form of the grounds for terminating the leave and shall specify the day (being a day not later than the date of the end of the period of the leave specified in the notification given in accordance with subsection (2) or (5) of section 7, section 13(2) or 14(2), as the case may be, nor, subject to the foregoing requirement, earlier than 7 days after the date of the receipt by the employee concerned of the notice) by which the employee must return to work.