7. (1) The meetings of the Board shall be held at such times and places and in such manner as may be prescribed: Provided that, until so prescribed, such meetings shall be held at such times and places as may be determined by the Chairman. (2) To constitute a quorum at a meeting of the Board, not less than five members shall be present. (3) All meetings of the Board shall be presided over by the Chairman and, in his absence, by the Vice-Chairman and, in the absence of both, by a member authorised in writing by the Chairman. (4) No act or proceeding of the Board shall be invalid or be called in question merely on the ground of any vacancy in, or any defect in the constitution of, the Board.