RB84:
AFAIK its not law that your employer HAS to pay you average earning’s over 12 weeks for holiday pay but many are now doing it as it is seen as best practice after courts have found in favour of the Employee’s when they challenged it, as they did with Stobarts.So rather than be faced with a big court settlement in the future employers have started paying it to avoid problems later that’s what I heard anyway but I may be wrong.
Look at the Gov /uk site regarding holiday pay it states people working irregular hours holiday pay is calculated on previous 12 weeks average, any weeks missed in that 12 it goes back another 2 eg:- off work or not paid for 2 weeks in the previous 12 it is then calculated over 14 weeks.