Any body mentioned in the last foregoing paragraph shall have power to act notwithstanding any vacancy among its members.

All acts done at any meeting of any such body shall, notwithstanding that it is afterwards discovered that there was a defect in the appointment or disqualification of a person purporting to be a member thereof, be as valid as if that defect had not existed.

Nothing in sub-paragraph (1) of this paragraph shall affect any requirement as to the number of members necessary to constitute a meeting of any such body as aforesaid.