Rivers of Blood

In the most notorious speech of postwar British politics, the right-wing Conservative M.P., Enoch Powell, spoke against equal opportunities legislation, and in favour of restricting immigration and encouraging the voluntary repatriation of existing immigrants.

The BBC recently devoted a full-length documentary to the speech and its impact:
Part 1
Part 2
Part 3
Part 4
Part 5
Part 6

Key phrases from the speech are:

Those whom the gods wish to destroy, they first make mad. We must be mad, literally mad, as a nation to be permitting the annual inflow of some 50,000 dependants, who are for the most part the material of the future growth of the immigrant descended population. It is like watching a nation busily engaged in heaping up its own funeral pyre. So insane are we that we actually permit unmarried persons to immigrate for the purpose of founding a family with spouses and fiancées whom they have never seen. [. . .] As I look ahead, I am filled with foreboding. Like the Roman, I seem to see "the River Tiber foaming with much blood". That tragic and intractable phenomenon which we watch with horror on the other side of the Atlantic but which there is interwoven with the history and existence of the States itself, is coming upon us here by our own volition and our own neglect. Indeed, it has all but come. In numerical terms, it will be of American proportions long before the end of the century. Only resolute and urgent action will avert it even now. Whether there will be the public will to demand and obtain that action, I do not know. All I know is that to see, and not to speak, would be the great betrayal.