12. Where the Court orders a general meeting of creditors to be summoned under rule 5 of the First Schedule to the Law, it shall be summoned as the Court directs, and in default of any direction by the Court the Registrar shall transmit a sealed copy of the order to the trustee (or, as the case may be, the Official Receiver) ; and the trustee or Official Receiver shall, not less than seven days before such meeting, send by post a copy of the order to each creditor at the address given in his proof, or, when he shall not have proved, at the address given in the list of creditors by the debtor, or such other address as may be known to the trustee or Official Receiver.