Employment Protection (Consolidation) Act 1978

4 (1) This paragraph shall apply if there are normal working hours for an employee when employed under the contract of employment in force on the calculation date, and he is required under that contract to work during those hours on days of the week or at times of the day which differ from week to week or over a longer period so that the remuneration payable for, or apportionable to, any week varies according to the incidence of the said days or times.

(2) The amount of a week's pay shall be the amount of remuneration for the average weekly number of normal working hours (calculated in accordance with sub-paragraph (3)) at the average hourly rate of remuneration (calculated in accordance with sub-paragraph (4)).

(3) The average number of weekly hours shall be calculated by dividing by twelve the total number of the employee's normal working hours during the period of twelve weeks—

(a) where the calculation date is the last day of a week, ending with that week ;

(b) in any other case, ending with the last complete week before the calculation date.

(4) The average hourly rate of remuneration shall be the average hourly rate of remuneration payable by the employer to the employee in respect of the period of twelve weeks—

(a) where the calculation date is the last day of a week, ending with that week;

(b) in any other case, ending with the last complete week before the calculation date.