Who can an employee compare herself with? 




The person the woman compares herself with is called a comparator and must be a man (or men) in the same employment. Normally, but not always, the comparator will be at the same physical workplace. It is helpful to choose a comparator whose circumstances are most similar to your own, to reduce the chances that the pay difference can be explained by factors other than sex. There is no need to identify the man by name at the outset.



An employee can choose her own comparator, and she can choose more than one, as long as they are engaged in “the same employment” (section 79, EA 10). They need not both be employed over the same time period (section 64(2), EA 10), so there is nothing in law to stop a woman using a comparator who has left the organisation (although there may be practical problems relating to evidence gathering and so on). 




After a TUPE transfer, a transferring employee can compare herself with a comparator whose employment did not transfer, although a claim against a transferee based on unequal pay before the transfer must be brought within six months of the transfer date (Gutridge v Sodhexo [2009] IRLR 72).


A woman cannot compare herself with a successor to her post, since the comparison process must involve a “concrete appraisal” of work actually performed (Walton Centre for Neurology and Neurosurgery NHS Trust v Bewley [2008] ICR 1047).




In Allonby v Accrington & Rossendale College [2004] ICR 1 328, the ECJ ruled that agency worker Debra Allonby could not compare her pay to that of a directly employed male colleague working alongside her. (Nowadays, a qualifying agency worker has equal pay rights under the Agency Worker Regulations 2010, see Chapter 2). 




The presence of some men doing the same work as women for the same pay will not stop an equal value claim by the women, comparing their jobs with the jobs of other better-paid male workers (Pickstone v Freemans [1988] IRLR 357). In Home Office v Bailey and others [2005] IRLR 369, the Court of Appeal ruled that female support officers could bring an equal pay claim using male governors as comparators, even though about 50% of support officers were male.
If such a claim succeeds, the low-paid men working alongside the women doing the same job can also claim the higher rate, known as “piggy-backing”. An example would be male shop workers in a claim comparing mainly female shopworkers with higher paid, mainly male warehouse staff, such as the ongoing retail claims against Asda, Tesco and Sainsbury’s. 



Where a woman has evidence of direct (but not indirect) sex discrimination in relation to her pay, but there is no actual comparator doing equal work (so that the sex equality clause cannot operate) she can claim direct sex discrimination based on a hypothetical comparator (section 71, EA 10). The following example is taken from the EHRC Code of Practice:




A woman has to identify a man “in the same employment” doing equal work to bring an equal pay claim. Section 79, EA 10 says that a woman can compare herself with a man employed:




• by the same employer at the same establishment or workplace; 


• by the same employer at a different establishment or workplace, where common terms and conditions generally apply, for example at another branch of a store; or




• by an associated employer, for example, a subsidiary. 




EU law also allows a woman to compare herself to a man who is not in the same employment, as long as the difference in pay is attributable to a single source with the power to rectify discriminatory pay differences (Beddoes v Birmingham City Council [2010] UKEAT 0056/10/0905 and Glasgow City Council v UNISON [2014] IRLR 532). 



This was applied most recently in a landmark ruling, Asda Stores v Brierley & Ors [2017] UKEAT/0011/17/DM, supported by the GMB. The EAT confirmed that 7,000 Asda store workers (mainly women) can compare themselves with higher paid Asda distribution workers based at depots. The single source identified as capable of rectifying the discrimination is the parent company, Walmart. As the EAT noted, Walmart could change the pay arrangements for both groups of workers “at the stroke of a pen, or more likely the click of a mouse”. 


As long as there is a “single source” of pay decision-making, an employee can be a valid comparator even if their pay is worked out in a different way. For example, the Asda distribution workers’ pay is negotiated through collective bargaining, whereas the women’s’ pay is imposed top down by the Asda board without negotiation. This difference did not stop the men being appropriate comparators in the Asda litigation.

There is no definition of “establishment” in the EA 10, but it is not restricted to a single physical location. “Same establishment” broadly means the same place of work (City of Edinburgh Council v Wilkinson [2012] IRLR 202).

If there is no appropriate comparator at the same establishment, EU law allows a hypothetical comparator to be used (Dumfries & Galloway Council v North [2013] UKSC 45).