In the event of a vacancy in the office of Lord Clerk Register, or in his absence from any cause, the Principal Clerk of Session, or in the event of a vacancy in that office, or in his absence from any cause, such person as the Secretary of State may designate for the purpose, shall have and may exercise all the powers and duties at or in connection with the election of representative peers of Scotland heretofore belonging to or exercised or exercisable by the Lord Clerk Register : Provided that the duties heretofore discharged by the staff of the Record Department in connection with such election shall continue so to be discharged.