Subject to section 12, a decision taken by the Council or an act performed under that decision is not invalid merely by reason of-

a)a)any irregularity in the appointment of a councillor;

b)b)a vacancy in the Council; or

c)c)the fact that any person not entitled to sit as a councillor sat as such at the time when the decision was taken provided such decision was taken by a majority of the councilors present at the time and entitled so to sit, and those councillors at the time constituted a quorum.