Can an employee use their predecessor or successor as the comparator in an equal pay claim?
A female employee making an equal pay claim under the "equality of terms" provisions of the Equality Act 2010 must compare themselves with at least one man doing equal work. This can be either someone employed in the organisation at the same time as the employee, or their predecessor. However, the Employment Appeal Tribunal held in Walton Centre for Neurology and Neurosurgery NHS Trust v Bewley  IRLR 588 EAT (which was decided under the now repealed Equal Pay Act 1970) that a woman cannot use their successor as a comparator.
Employees have the option of bringing a direct sex discrimination claim under s.13 of the Act in relation to contractual pay, rather than a claim under the "equality of terms" provisions. This allows the employee to compare their pay to that of a hypothetical male comparator. It may be possible for an employee to use their successor's pay as evidence in a claim under s.13; this remains to be tested by case law.