The possession of two channels by the BBC has upset the competitive balance between BBC and ITV in several ways, some obvious and some more subtle. For example, if ITV is providing an evening programme which is serious but not very popular, it can no longer expect to hold its audience on the basis that the opposition also will be a serious rather than a popular programme; for this will only be true of one of the two BBC channels, while the other, following the principles of complementary programming, will very often be popular and drawing off many viewers. Although the overall position has not yet seriously changed, it is natural that the companies should fear that, without a second ITV channel, a position might eventually be reached in which each of the three channels took a third of the audience. This consideration would apply with even greater force if the fourth channel were to be allocated in such a way that the ITV companies faced three competitors, rather than two as now, for the audience. Serious difficulties would obviously arise if there were a downward drift of audiences, not only for the companies but also for the Authority which would find it harder to impose its present public service requirements on the companies in such a situation.