An act or decision of the Board is not invalid only—
(a) because of a vacancy in the membership of the Board, including a vacancy arising from the failure to appoint a director; or
(b) because of a defect or irregularity in, or in connection with, the appointment of a director or the appointment of an acting director; or
(c) in the case of an acting director—on the grounds that the occasion for the person to act had not arisen or had ceased.