There shall be in the office of collective bargaining a board of collective bargaining, which shall consist of seven members. Two members of the board shall be city members, two members of the board shall be labor members, and three members of the board, of whom one shall be chairman, shall be impartial members. The mayor shall have the power to appoint the city members of the board to serve at his pleasure, and the labor members of the board from designations by the municipal labor committee. Each labor and city member shall have an alternate, who shall be appointed and removed in the same manner as the member for whom he is the alternate. The chairman and other impartial members shall be elected by the unanimous vote of the city and labor members, and shall serve for three year terms, provided, that of the impartial members first elected, the chairman shall serve for a term ending on January first, nineteen hundred seventy, one member shall serve for a term ending on January first nineteen hundred sixty-nine, and one member shall serve for a term ending on January first, nineteen hundred sixty-eight.
Notwithstanding any other provision of law, a labor member may not be removed from the board except upon request of the municipal labor committee, or except for cause, as hereinafter provided. Any member may be removed for cause by a majority of the entire board, including at least one city member and one labor member, after having been given a copy of the charges against him and an opportunity to be heard in person or by counsel in his defense upon not less than ten days' notice. Vacancies in the office of a city member or a labor member shall be filled in the same manner as herein provided for appointment. Vacancies in the office of an impartial member occurring otherwise than by expiration of term shall be filled by unanimous vote of the city and labor members for the unexpired balance of the term.