means any day excluding a Saturday, Sunday, public holiday and the days in the period from 16 December to 7 January, both days inclusive; when any particular number of days is prescribed for the doing of any act, the number of days must be calculated by excluding the first day and including the last day, unless the last day falls on a Saturday, Sunday, public holiday or on a day during the period 16 December to 7 January, in which event the number of days must be calculated to exclude the first day and also such last day;