From and after the passing of this Act no select Vestry shall be formed under the provisions of the Church Building Act, and every such select Vestry already formed under such provisions shall be and is hereby declared to be abolished, and all the powers and provisions therein enacted relative to such select Vestries shall henceforth cease and determine, provided that all matters and things done by any such select Vestry in pursuance of any powers given them by such Acts, or any of them, shall be and remain as valid as if such select Vestry had not been abolished.