How did Shaw make good use of the gathering of people in Act 1?

Besides introducing the major characters of the play, this act introduces socioeconomic class as a central theme of Pygmalion. As a socialist, Shaw was particularly concerned with exploring and exposing the power divide between the poor and the rich. By setting the play in London, Shaw chooses to deal with a society that is particularly stratified. British class-consciousness is based not only on economic power, as it is in many other societies, but also on history (historic class differences). The play highlights British people's recognition of accents to differentiate among themselves not only geographically (a Welsh accent is distinct from a Scottish accent, which is distinct from a Surrey accent), but also to distinguish (on another but related dimension of accents) the various social classes.