Possible Clues:

• Very obviously calling, and loud always initially?
• Hardly tight-lipped
• Loud, and very close to home? Not initially
• Expressive
• First of visitors obscuring entrance in pub is outspoken
• More than willing to speak up
• Outspoken pub reducing headcount by 90%?
• Strident singing part..
• Track singer will provide
• Not afraid to speak out