In every case in which it is so declared that no portion of the pews or seats shall be let for any payment of money, a sufficient endowment or stipend of not less than one hundred pounds per annum shall be secured to the incumbent by or to the satisfaction of the Ecclesiastical Commissioners, and in every case in which a portion only of the pews or seats may not be so let, an endowment or stipend of such amount as the said Commissioners may determine, regard being had to the proportion of pews or seats which may not be so let, shall be in like manner secured.