"Whoever becomes the head of the National Theater finds himself in a position like that of Nelson's Column - pigeons dump on you because you're there"

This quote by Peter Hall is a humorous method of describing the troubles of being the head of the National Theater. It is a comparison to Nelson's Column, a monolith in London that is typically used as a perch by pigeons. The implication is that the head of the National Theater will go through criticism and analysis, just as the pigeons dump on Nelson's Column. This is a metaphor for the troubles of the task, as the head of the National Theater will be expected to make challenging decisions and will be judged roughly for them. It is a suggestion that the job is not a simple one, and that the head of the National Theater will require to be gotten ready for criticism and examination.