In any case in which the consent of the patron of any benefice shall be required to the exercise of any power given by this Act, or in which any notice shall be required by this Act to be given to the patron of any benefice, and the advowson and right of patronage of such benefice shall be part of the possessions of the duchy of Cornwall, the consent of the patron of such benefice to the exercise of such power shall be testified and such notice shall be given respectively in the manner herein-after mentioned; (that is to say,) the instrument by which the power shall be exercised shall be executed by and any such notice shall be given to the duke of Cornwall for the time being, if of full age, but if such benefice shall be within the patronage of the crown in right of the duchy of Cornwall, such instrument shall be executed by and any such notice shall be given to the same person or persons who is or are by this Act authorised to testify the consent of the crown to the exercise of any power given by this Act in respect of any benefice in the patronage of the crown; and the execution of such instrument by and any such notice given to such person or persons shall be deemed and taken for the purposes of this Act to be an execution by and a sufficient notice to the patron of the benefice.