Chief Constable of the Police Service of Northern Ireland and another v Agnew and others

The Supreme Court dismissed the employer's appeal. The court held that, by virtue of the EU law principle of equivalence, claimants who enforce a right to four weeks' annual leave under the Working Time Directives are entitled to the more favourable limitation regime available under article 55(3) of the Employment Rights (Northern Ireland) Order 1996 (the “series” extension). The court read into regulation 43(2)(a) WTR (NI) the words necessary to permit a complaint presented in respect of a series of payments provided the last payment was within three months.

The court also held that whether there is a "series" is a question of fact; a series does not require contiguous or regular payments and is not necessarily broken by a gap of more than three months or by an intervening lawful payment, so long as the payments are linked by a common fault or unifying vice. Finally, the court confirmed that the four-week entitlement deriving from the Directives attracts "normal" pay which may include overtime and that questions of reference period and detailed calculation are factual matters for the tribunal.

The claimants, a large group of police officers and civilian staff of the Police Service of Northern Ireland, sought arrears of holiday pay dating back to November 1998. Their case was that, for the four weeks of annual leave derived from the EU Working Time Directives, holiday pay should have reflected "normal" pay and therefore included payments for regular overtime. The employers had paid only basic pay for holiday weeks. The principal relief sought was recovery of historic underpayments.

Procedural history: certain preliminary issues were tried first at the Industrial Tribunal (judgment 2 November 2018, [2018] NIIT 112/16IT). The Court of Appeal dismissed the employers' appeal ([2019] NICA 32). The present appeal to the Supreme Court concerned two main issues: (i) whether police officers could rely on the article 55(3) "series" extension (a point raising the EU principle of equivalence and, subsidiarily, whether police officers fell within the ERO definition of "worker" or otherwise had Article 14 ECHR protection); and (ii) the scope and legal meaning of a "series" for limitation purposes, including whether gaps of more than three months or lawful payments break a series. The court also addressed subsidiary issues about sequencing of different categories of leave, the correct mode of calculation where overtime is relevant and the appropriate reference period.

On equivalence, the Supreme Court held that claimants enforcing the Directive-derived four weeks' right may rely on the more favourable procedural regime embodied in article 55(3) ERO. The Court applied the CJEU tests of equivalence and concluded that the domestic article 55 procedure is a true comparator with enforcement under the Working Time Regulations (Northern Ireland), and that importing the "series" extension into regulation 43(2)(a) WTR (NI) 2016 (and the equivalent 1998 regulation) was an appropriate Marleasing-style corrective reading.

On the meaning of "series", the court held the word is ordinary English and whether a series exists is a factual question. A series may comprise payments at varying intervals and differing amounts, provided there is a sufficient unifying link (for example a consistent method of underpayment). A gap of more than three months or an intervening lawful payment does not automatically terminate a series where the lawful payment is itself connected to the same underlying fault. The court rejected the contention that contiguity or temporal regularity is a legal requirement for a series.

On the calculation and other practical points, the court confirmed that the four-week entitlement derived from EU law must aim to put the worker in a position, as to remuneration, comparable to periods of work; consequently, regular overtime and similarly intrinsically linked payments may be part of "normal" pay. The court endorsed the Court of Appeal's view that the use of calendar days as a divisor where the leave denominator is working days is not generally appropriate and that reference period and precise calculations are factual matters for the tribunal. The court therefore dismissed the appeal and remitted remaining matters to the tribunal for factual determination.

Appeal dismissed. The court held that (i) by the EU principle of equivalence claimants enforcing the four-week WTD-derived holiday right may rely on the more favourable article 55(3) ERO "series" limitation, and the WTR (NI) time limit should be read to permit claims in respect of a series where the last payment was within three months; (ii) the meaning of a "series" is a question of fact, does not require contiguity or regularity, and is not necessarily broken by a gap of over three months or by an intervening lawful payment if the payments are linked by a common fault; and (iii) the Directive-derived four weeks' holiday pay may include overtime and related payments and detailed calculations and reference periods are for the tribunal.

Preliminary issues decided by the Industrial Tribunal (judgment 2 November 2018: [2018] NIIT 112/16IT). The Court of Appeal dismissed the employer's appeal on the issues before this court: [2019] NICA 32. The Supreme Court dismissed the appeal on 4 October 2023: [2023] UKSC 33.