Provided also, and be it further enacted, That the Permanent Staff of the said Two Regiments of London Militia, now receiving Pay, shall continue to receive such Pay, and to be subject to the Provisions of the said Two Acts of the Thirty-sixth and Thirty-ninth Years of the Reign of His late Majesty, for One Calendar Month after the passing of this Act; and that" from and after the Expiration of the said Month this Act shall commence and take Effect, with regard to the Permanent Staff of the said Regiment to be raised by virtue of this Act, and the Pay to be received by such Staff: Provided always, that the Serjeant Majors, Serjeants, Corporals, Drum Majors and Drummers, now on Permanent Pay, in the said Two Regiments, and who may be desirous to serve in the said Regiment to be raised by virtue of this Act, and who shall take the Oath hereby required to be taken by Serjeants, Corporals, and Drummers, shall with the Approbation of the Commanding Officer of the said Regiment, but not otherwise, be at Liberty so to do; but no Vacancy occasioned by the Death, Discharge, or Removal of any such Serjeant, Corporal, or Drummer shall be filled up, until the Number of such Serjeants, Corporals, and Drummers shall be reduced below the Number of Serjeants, Corporals, and Drummers which the said Regiment is allowed by virtue of this Act.