(1) A councillor (other than the mayor) holds office for 4 years, subject to this Act.
(2) The office of councillor--(a) commences on the day the person elected to the office is declared to be so elected, and(b) becomes vacant on the day appointed for the next ordinary election of councillors, or on the occurrence of a casual vacancy in the office.
(3) A person elected to fill a casual vacancy in the office of councillor holds the office for the balance of the predecessor's term.