"And that will increasingly dawn on people. The demand for controlling the commanding heights will grow"

In this quote, Barbara Castle is suggesting that people will gradually concern realize the importance of managing the most influential and effective sectors of society. This might describe industries, institutions, or perhaps political systems. Castle believes that as this understanding grows, there will be a greater desire for individuals or groups to have control over these "commanding heights." This might be driven by a desire for power, influence, or the capability to form the instructions of society. Castle's words imply that this demand for control will continue to increase in the future, as individuals become more familiar with the significance of these commanding heights.