20.—(1) This rule applies where the respondent does not intend to call as a witness—
(a)any person whose statement has been served on the appellant as part of the evidence for the respondent; or
(b)any person in respect of whose evidence he has served notice under rule 48 below.
(2) Where this rule applies, unless the appellant waives the requirement, the respondent shall—
(a)serve notice in writing on the appellant that he does not intend to call that person; or
(b)tender that person at the hearing of the appeal for cross-examination by the appellant.