Following a number of recent cases, the Court of Appeal has held that where voluntary overtime is sufficiently regular to amount to “normal” remuneration, it should be taken into account when calculating holiday pay.
Various ambulance crew worked 'voluntary' overtime. It was entirely voluntary - they were free to choose whether or not to do it. On a holiday pay claim, the court agreed that as it was sufficiently regular and settled for payments made in respect of normal remuneration, it should be taken into account when calculating holiday pay.
Flowers v East of England Ambulance Trust