Active Control Technology (ACT) is not a new subject; it has been utilised in engineering circles for over a century in various guises, the first application of any significance being the steam engine governor. The history of the subject is accordingly long and is well referenced, and we shall depart from the time-honoured rigmarole of providing a detailed survey of early developments by directing our audience instead to Ref. 1 where such a survey may be found. In similar mildly unconventional vein, we note that this platform, and many others like it in this country and elsewhere, has been used many times by eminent individuals to expound their own idiosyncratic views as to how ACT should be defined in its constituent functions and how, in turn, these might possibly be applied without much in the way of reference to what has been done or to the many practical limitations. While our own views presented here will also be idiosyncratic, we shall attempt to relate what we say to that which has been achieved in actual applications and, based on these achievements, to what might follow in the foreseeable future.