No, held the ECJ in Greenfield v The Care Bureau Ltd.
The Claimant's working hours and days varied from week to week. She took 7 days' paid leave at a time when she was working one day a week (the equivalent of 7 weeks' leave). Her employer said this exhausted her entitlement. She then increased her hours to 12 days on, 2 days off each fortnight. After her employment ended, she claimed a payment for accrued but untaken annual leave.
The employment tribunal upheld her claim, but following an appeal and application for reconsideration, referred the matter to the European Court of Justice (ECJ).
The ECJ held that annual leave must be calculated in accordance with a worker's contractual working pattern, and the hours, days (and fractions thereof) actually worked. However, the taking of leave accumulated in one period has no connection to the working hours in the later period when leave is actually taken.
There was already authority that a reduction from full-time to part-time working should lead to no reduction in the amount of leave a worker has already accumulated (Zentralbetriebsrat der Landeskrankenhauser Tirols, 2010). An employer must therefore distinguish between different periods of different working patterns and calculate the leave that accumulates in each period separately, taking the same approach whether this is during employment, or after it has ended.