Mrs. Khansa El-Nur, wife of the leader of the abortive coup in the Sudan, left London for Khartoum today only minutes after being told her husband had been executed by a firing squad. An official from the Sudan Embassy boarded the aircraft carrying Mrs. El-Nur to inform her that an official announcement had just been received. After a tearful scene while the aircraft waited, Mrs. El-Nur decided to continue her trip.