J Mireku v London Underground Limited

The Employment Appeal Tribunal considered the proper causation test under Regulation 5(2)(a) of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 and whether it should depart from the recent EAT authority in Augustine v Data Cars Ltd [2025] ICR 19. The Tribunal concluded that it should follow Augustine and the Inner House decision in McMenemy v Capita Business Services Ltd [2007] SC 492, reading Regulation 5(2)(a) as requiring that less favourable treatment be "on the sole ground" that the worker is a part-time worker. The Tribunal also held that, on the facts found by the Employment Tribunal, the claimant’s overtime cancellation was attributable to administrative confusion and his unusual budgetary/management arrangements rather than to his part-time status, and that the claimant had not established a comparable full-time worker. The appeal was therefore dismissed.

Background and parties. The appellant, Mr Mireku, a part-time Customer Service Supervisor, brought claims under the Part-Time Workers Regulations 2000 and for breach of contract arising from refusal and cancellation of overtime and related detriments. The respondent was London Underground Limited.

Procedural history. The Employment Tribunal sitting at London South dismissed the part-time worker complaint and the breach of contract claim; a corrected judgment followed. The appellant appealed to the Employment Appeal Tribunal. The EAT heard a sift and the substantive appeal, during which the recent EAT decision in Augustine v Data Cars Ltd [2025] ICR 19 was central.

Nature of the claim and relief sought. The appellant complained of less favourable treatment contrary to Regulation 5 of the Regulations (and sought to rely on a series of alleged detriments, including cancellation of overtime and restrictions on overtime), and also sought extensions of time for earlier acts.

Issues framed.

• What is the correct causation test for Regulation 5(2)(a): must part-time status be the sole ground for the treatment (McMenemy/Augustine) or is it sufficient that part-time status be an effective or predominant cause (Sharma/Carl)?
• Did the Employment Tribunal err in law in its findings on causation and in relation to comparators and time limits?

Court’s reasoning and conclusions. The EAT reviewed the competing lines of authority and, applying the guidance in British Gas Trading Ltd v Lock & Another [2016] ICR 503 on when the EAT departs from its prior decisions, concluded it should follow Augustine, which read the Regulations consistently with McMenemy and held that the less favourable treatment must be "on the sole ground" of part-time status. The EAT further held that even applying the alternative "effective and predominant cause" test, the Employment Tribunal’s factual findings — that the overtime cancellation resulted from administrative confusion linked to the claimant’s atypical managerial/budgetary position and that his comparators were not truly comparable — were incompatible with a finding that part-time status caused the treatment. The EAT therefore dismissed the appeal and declined to remit the matter for rehearing.

This appellate appeal is dismissed. The EAT followed its prior reasoning in Augustine and McMenemy that Regulation 5(2)(a) requires less favourable treatment to be "on the sole ground" that the worker is a part-time worker. On the facts found by the Employment Tribunal, the cancellation of overtime was attributable to administrative confusion and the claimant’s unusual budget/management arrangements rather than to his part-time status; additionally, the Tribunal found no comparable full-time worker, which was fatal to the claim.

Claim presented to the Employment Tribunal (London South) on 26 December 2022; hearing before Employment Judge Curtis 12 October 2023; ET judgment dated 29 November 2023 (sent 5 December 2023) dismissed the part-time worker claim; corrected judgment issued 1 February 2024 and reconsideration dismissed. Notice of Appeal to the EAT received 11 January 2024; a sift decision was given by Andrew Burns KC on 29 February 2024; appeal heard by the EAT and judgment handed down 29 April 2025. The EAT considered and applied its recent decision in Augustine v Data Cars Limited [2025] ICR 19 (itself subject to further appeal to the Court of Appeal, hearing noted in the judgment).