This is an area of study where there are advantages to be gained by applying the approach recommended in Chapter 1, deriving, from the work of Graham Allison, of exploring the extent to which the concurrent use of apparently conflicting theories provides com-Plementary insights. Blowers' use of such an approach in his pollution study influenced one of the authors to try something similar (hill, Aaronovitch and Baldock, 1989). Blowers' observations on the method are instructive