It is unlawful for any person to wilfully disrupt or disturb by any means whatsoever an official body or meeting of persons duly convened for a lawful purpose. For the purpose of this section, wilfulness of the disruption or disturbance shall be presumed when such activity persists after the person or persons involved have been warned by the acting chairman of the meeting to cease the objectionable activity. (Ord. 1244 § 2 (part), 1985: Ord. 506 § 10, 1969).