12.—(1) A ground shall not be regarded as an objective ground for the purposes of any provision of this Part unless it is based on considerations other than the status of the employee concerned as a part-time employee and the less favourable treatment which it involves for that employee is for the purpose of achieving a legitimate objective of the employer and such treatment is appropriate and necessary for that purpose.

(2) For the avoidance of doubt, a ground which does not constitute an objective ground for the purposes of section 9(2) may be capable of constituting an objective ground for the purposes of section 11(2).