"(2) In this section – "concealment case" means a case where - (a) the employer deliberately concealed from the woman any fact (referred to in this section as a "qualifying fact") - (i) which is relevant to the contravention to which the proceedings relate, and (ii) without knowledge of which the woman could not reasonably have been expected to institute the proceedings, and (b) the woman did not discover the qualifying fact (or could not with reasonable diligence have discovered it) until after - (i) the last day on which she was employed in the employment, or (ii) the day on which the stable employment relationship between her and the employer ended, (as the case may be)"