20. Where under section eleven of the Act (which relates to statements of earnings, etc.) an order is directed to the defendant or to a person appearing to be an employer of the defendant or where under this Part of these Rules a copy of an order is to be served or a notice is to be given to any person—
(a)service may be effected on, or notice may be given to, a person other than a corporation by delivering it to the person to whom it is directed or by sending it by post in a letter addressed to him at his last known or usual place of abode or, in the case of a person appearing to be an employer of the defendant or of a person to whom the related attachment of earnings order is directed, at his place of business;
(b)service may be effected on, or notice given to, a corporation by delivering the document at, or sending it to—
(i)such office or place as the corporation may, for the purpose of this Rule, have specified in writing to the court which made the order or the related attachment of earnings order in relation to the defendant or to the class or description of persons to which he belongs, or
(ii)the registered office of the corporation if that office is in England and Wales or, if there is no registered office in England and Wales, any place therein where the corporation trades or conducts its business.