Answer: Everyone turns, stops dancing and watches them silently.
The crowd is too preoccupied with dancing to notice when the party first enters and just keep on dancing. Soon after they enter, the crowd turns around, whilst dancing, and sees the party. The crowd stops dancing and the music stops playing, everything is silent. The crowd watches and waits for something, though nobody knows quite what. Nobody knows what to do, as they have never had such guests as these. Finally, Sir William Lucas steps forward to greet them, and the party walks to the other side of the hall. The music then restarts and everyone starts dancing again.