The Appellant, having made protected disclosures during her trial period, was dismissed by the Respondent, which cited, as its reason for the dismissal, the Appellant's inadequate performance. On the Appellant's complaint in the ET of unfair dismissal under s 103A Employment Rights Act 1996 ("ERA"), the ET found that, since the decision-maker had dismissed her on the ground of a genuine belief that her performance had been inadequate, the reason for dismissal was her performance, meaning that s 103A ERA did not apply, and so it rejected her complaint. The EAT reversed this decision, holding that the reason for dismissal was the making of the protected disclosures; and the Court of Appeal allowed the Respondent's appeal, reinstating the ET's rejection of the complaint of unfair dismissal on the basis that a tribunal required to determine the reason for dismissal under s 103A ERA was obliged to consider only the mental processes of the employer's authorised decision-maker. The Appellant appealed.

The Supreme Court identified that the key question was, "In a claim for unfair dismissal can the reason for the dismissal be other than that given to the employee by the decision-maker?", and it held unanimously that the answer was "Yes, if a person in the hierarchy of responsibility above the employee determines that she (or he) should be dismissed for a reason but hides it behind an invented reason which the decision-maker adopts, the reason for the dismissal is the hidden reason rather than the invented reason". Accordingly, the part of the Court of Appeal order that allowed the Respondent's appeal would be set aside, and the EAT's order would be restored.