Complex sentence: Noonan then started to put his own men on the doors and by the late 1980s 80% of the Manchester nightlife security was said to be controlled by Desmond Noonan and his family.
Split into simpler sentences: Noonan then started to put his own men on the doors. By the late 1980's, 80% of the Manchester nightlife security was said to be controlled by Desmond Noonan and his family.