Theatre plays a great role in understanding and analyzing history. The dramatization of the events taken place during a specific period of time enables the audience to make their own subjective interpretation of these events. Such dramatic portrayal offers a comprehensive vision of history offered by all categories of the society. Reading Margaret Thatcher’s era through studying theatrical works helps us to understand well that period of history. In fact, enhancing the British economic system is the most prominent feature of Thatcher’s era. One of the most controversial policies of Thatcher's economic programme was curbing the Mining Trade Unions’ power. The Thatcherite economic system excluded many groups such as the ethnic minorities, women, unemployed and the low-paid to participate in decision-making. From here emerged the idea of unfairness, struggle, and the government's prejudice against specific categories in the society which inevitably led to the social imbalance in the British society of that time. Thatcher was concerned with supporting the operation of the market economy by freeing up the supply of Labour, by restricting the collective rights of workers in trade unions and by curbing their political power. All these measures led to the damage of trade unions as they were no longer an effective political power. To explore how the economic policy of curbing the trade unions’ power affects the ordinary social life of the British society of the 80s, David Edgar’s play That Summer (1987) is analyzed in the light of the new historicist literary theory. Such critical reading of the play shows to what extent this policy is a failure by depicting the misery and suffering of the miners and their families. The playwright chooses to be by the side of the miners expressing the amount of oppression and marginalization they were exposed to as a result of saying "No" to Thatcher's unfair measures.