A casual vacancy arising in the office of a Member appointed by the Authority shall, unless it is not reasonably practicable to do so, be filled by the appointment of a Member by the Authority and any such appointment shall be made in accordance with the requirements of article 6.

A Member appointed to fill a casual vacancy under this article shall hold office (unless he previously dies or otherwise ceases to be a Member) during the remainder of the term for which the member whom he replaces was appointed.