How does the themes and staging reflect the times they were written?
Thematically, it looks at the various problems of Australian society. The following are all problems which can be associated with the 1970's period.
Simmonds is a representative of police corruption, and common immorality. Ross is a symbol of the institution, and how it cannot prepare an individual for the real world. Kenny, a representation of the archetype male, and his relationship shows the common problems of male dominance, wife abuse, and female oppression. The removalist himself is a symbol of the 'everyday-man', one who doesn't want to be involved, and merely sits on the fence.
Climatically, the play shows Ross's eventual descent from good cop, to bad cop. The good intentions of the institution are reduced to rubble as the play finishes with the death of Kenny, and utter hysteria. This descent in particular, highlights the themes and symbols of the play.
This should get you started.