In this division—
"ordinary working day" means a day on which an employee would ordinarily be
required to work.
"show holiday" means—
(a) a public holiday appointed for an annual agricultural, horticultural or industrial show under the Holidays Act 1983 , section 4 ; or
(b) for a district in which a holiday is not appointed for an annual agricultural, horticultural or industrial show—the ordinary working day agreed on by the employer and employee that is to be treated as a show holiday for all purposes.