No matter or thing done and no contract entered into by any county authority, and no matter or thing done by any member of any such authority, or by any officer of such authority or other person whomsoever appointed by and acting under the direction of such authority, shall, if the matter or thing were done or the contract were entered into bona fide for the purpose of executing this Act, subject them or any of them personally to any action, liability, claim, or demand whatsoever, and any expense incurred by any such county authority, member, officer, or other person acting as last aforesaid shall be paid by the county authority;
Provided that nothing in this section shall exempt any member of any county authority from liability to be surcharged with the amount of any payment which may be disallowed by the auditor in the accounts of such authority, and which such member authorised or joined in authorising.