ABSTRACT
Starkie argues that secular economic and social trends, which on the whole were of a fairly smooth nature, do not by themselves explain one important feature of post-war road and traffic policies, namely the tendency towards distinct, quite sudden but infrequent change. However, by combining the forces of circumstance with the role of pressure groups, we are able to explain more easily such marked changes in policy. In these circumstances, alteration to policies is unlikely to be brought about by gradual modification. On the contrary, the tendency is for a firm change of policy to take place only when a sufficient head of steam has been produced by lobbyists capitalising upon favourable pressures from economic, social and intellectual forces (Starkie 1982:152-3).
