J Mireku v London Underground Limited

For regulation 5(2)(a) of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000, less favourable treatment must, unless a higher court decides otherwise, be on the sole ground that the worker is part-time. The EAT should ordinarily follow a recent EAT decision which has resolved earlier inconsistency, unless an established exception justifies departure.

In any event, a claim fails under either a sole-ground or effective-and-predominant-cause approach where the tribunal finds that the treatment resulted from a reason wholly independent of part-time status. The claimant must also identify an actual comparable full-time worker satisfying the Regulations.

The appellant, a part-time Customer Service Supervisor working under a job-share arrangement, complained that London Underground had restricted and cancelled overtime opportunities contrary to regulation 5 of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000.

The Employment Tribunal upheld two early allegations but held them out of time. It dismissed the allegation concerning the cancellation of overtime on 19 October 2022. It found that staff had been uncertain how to process the request because the appellant worked in one area while another manager held the overtime budget. It also found that the proposed full-time comparators were materially differently situated.

The appeal challenged the causation test under regulation 5(2)(a), contending that part-time status need only be an effective and predominant cause. The central issue was whether the EAT should depart from Augustine, and whether the Tribunal’s findings were capable of satisfying either causation test.

1. Appeal dismissed. The EAT would not depart from Augustine v Data Cars Limited [2025] ICR 19. Under the principles in British Gas Trading Ltd v Lock & Another [2016] ICR 503, previous EAT decisions are ordinarily followed unless an established exception applies. Although earlier EAT decisions had differed on the substantive causation question, Augustine had resolved the distinct precedent question after full consideration of the authorities.

2. Accordingly, unless and until a higher court decides otherwise, regulation 5(2)(a) requires the claimant’s part-time status to be the sole ground of the less favourable treatment. The EAT followed Augustine in treating the Inner House decision in McMenemy v Capita Business Services Ltd [2007] SC 492 as the governing approach for legislation operating throughout Great Britain.

3. The Tribunal’s factual findings independently defeated the appeal. It found that the overtime cancellation resulted from staff uncertainty and error caused by the unusual arrangement under which a manager other than the budget-holder supervised the appellant’s work. It had also found that this arrangement was wholly unrelated to part-time status. Those findings excluded part-time status both as the sole ground and as an effective or predominant cause.

4. There was a further, unchallenged obstacle. Regulation 5 requires a comparable full-time worker, and Carl v University of Sheffield [2009] ICR 1286 establishes that an actual, rather than hypothetical, comparator is required. The Tribunal had found the relied-on full-time workers materially differently situated. No ground of appeal challenged that conclusion.

• Employment Appeal Tribunal: Appeal dismissed: [2025] EAT 57.
• Employment Tribunal, London South: The part-time worker claim was dismissed in a judgment dated 29 November 2023 and sent to the parties on 5 December 2023. A corrected judgment on 1 February 2024 confirmed that the breach of contract claim was also dismissed for want of jurisdiction, and reconsideration was otherwise refused.