The court by which a hospital order is made may give such directions as it thinks fit for the conveyance of the patient to a place of safety and his detention therein pending his admission to the hospital within the period of 28 days referred to in section 376(6) of this Act; but a direction for the conveyance of a patient to a residential establishment provided by a local authority under Part IV of the [1968 c. 49.] Social Work (Scotland) Act 1968 shall not be given unless the court is satisfied that that authority is willing to receive the patient therein.