Possible Clues:

• In the auditorium confine one after another
• Where Ur is? N.I.?
• This is how to put Ulster behind bars. By the sound of it, one after the other
• By order of succession
• N.I., one after the other
• This seems to make N.I., one after the other
• Where do they shut one up, by the sound of it? Could it be NI?
• This might lead one to Ulster, one after the other
• N.I. one after the other
• Seamen following mobile unit, one after the other