Rebecca Thomas represents the respondent in Mireku v London Underground Limited [2025] EAT 57

42BR’s Rebecca Thomas successfully acted for the Respondent in the case of Mireku v London Underground Limited where the Employment Appeal Tribunal (EAT) reaffirmed that under the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 (SI 2000/1551), a claimant must show that part-time status was the sole reason for any less favourable treatment.

The case involved Mr Mireku’s claim that his overtime had been cancelled in breach of the PTW Regulations. The employment tribunal dismissed his claim, finding that the cancellation was unrelated to his part-time status. On appeal, Mr Mireku argued that the tribunal had applied the wrong causation test.

The EAT acknowledged historical inconsistency in the application of causation tests. While some earlier EAT decisions had adopted the “effective and predominant cause” test (Sharma and Carl), the Court of Session in McMenemy v Capita Business Services Ltd [2007] SC 492 had held that part-time status must be the sole cause of the treatment.

In Augustine v Data Cars Ltd [2024] EAT 117, Eady P conducted a thorough review of all these earlier authorities and concluded that, although she had expressed a preferences for a "effective and predominant cause" test, she was bound to follow McMenemy. Applying this precedent, the EAT in Mireku found no error in the tribunal’s approach.

The EAT further noted that, even if the effective and predominant cause test was applied there was no error and, in any event, Mr Mireku’s claim failed on another ground as the Tribunal had concluded that he had not identified a suitable full-time comparator.

The Court of Appeal has heard the Augustine case, and its forthcoming judgment may offer clarity on this issue. Until then, the McMenemy causation test must be followed. 

Mireku v London Underground Limited [2025] EAT 57 judgment 

13th May 2025

Rebecca Thomas

Call 1999