If an oath or affirmation is deemed by section 21 to have been validly taken, or made, on a day ( the relevant day ), by a person in relation to the appointment of the person to, or the holding by the person of, an office, the person is not required to take, subscribe or make after the day on which this Act commences, another oath or affirmation under this Act in relation to the same appointment to that office or, if that person has not ceased to hold the office after the relevant day, to the continued holding of that office.