4A member of a board shall vacate his office if he—
(a)ceases to be a member of the constituent water authority from which he was appointed in pursuance of section 84, or
(b)has, for a period of 12 consecutive months, been absent from meetings of the board, otherwise than by reason of illness or some other cause approved during that period by the board;
Provided that for the purposes of head (b) of this paragraph, the attendance of a member at a meeting of any committee of the board shall be treated as attendence at a meeting of the board.