Even ignoring the literal rivers of blood, Powell saw what was coming:
But while, to the immigrant, entry to this country was admission to privileges and opportunities eagerly sought, the impact upon the existing population was very different. For reasons which they could not comprehend, and in pursuance of a decision by default, on which they were never consulted, they found themselves made strangers in their own country.
They found their wives unable to obtain hospital beds in childbirth, their children unable to obtain school places, their homes and neighbourhoods changed beyond recognition, their plans and prospects for the future defeated; at work they found that employers hesitated to apply to the immigrant worker the standards of discipline and competence required of the native-born worker; they began to hear, as time went by, more and more voices which told them that they were now the unwanted.
Strangers in their own country; murdered in their own streets. The bloody foam covers the Tiber.