I have been doing some thinking about Mr. B and his motivations. It occurs to me that he has been visiting the Club for at least a few months. Until now he has paid visits only to girls who are at least eighteen years old. Perhaps he has spent time with Katie before, and built a bit of a rapport? This visit would mark a departure, however, as he is going to indulge a desire to sleep with a girl closer in age to his daughter (something he scarcely admits to himself he wants). It might need another girl involved, however, which would satisfy the desire for group sex and exhibition of a few participants.