71.—(1) For the purposes of these Rules a special finding is, where the particulars proved or admitted at the trial differ from those alleged in the charge but are sufficient to support a finding of guilty of the like offence as that charged, a finding of guilty subject to exceptions or variations specified in the finding.
(2) The court may not reach a special finding unless it appears that the difference is not so material as to have prejudiced the accused in his defence.