20.—(1) A solicitor appointed to act for a respondent in proceedings on a petition shall forthwith give notice of his appointment to the petitioner and lodge a copy of the notice in the election petitions office.
(2) Any notice required to be served on a respondent to a petition may be served—
(a)by delivering it or sending it by post to any solicitor who has given notice under the last foregoing paragraph that he is acting for the respondent; or
(b)if no such notice has been given, in the manner provided by section 162 of the Act.
(3) Any notice required to be served on the returning officer or the Director of Public Prosecutions in proceedings under these Rules may be served by delivering it or sending it by post to him.