This paper was originally written for the benefit of a single pharmaceutical company. However the company agreed when it was commissioned that it should be made generally available once it had been studied within that company, and this publication is the outcome.

I am extremely grateful to the Directors of several individual Medical Departments in Britain, on whose expertise the study is based. The conclusions and predictions are, however, my own responsibility. I trust they may be of interest to those in the pharmaceutical industry who have responsibility for the forward planning and organisation of the Medical Departments. Their accuracy and relevance, however, will not be able finally to be judged until the end of this century