The real tributaries of Enoch’s ‘rivers of blood’

What was in Enoch Powell’s mind when he made his explosive ‘rivers of blood’ speech on immigration 40 years ago this spring? His repetition of wild allegations against immigrants made by his constituents and his apocalyptic warnings of bloody racial conflict ended his front-bench career. Overnight Powell was transformed into a folk-hero for many and a hate-figure for others. Four decades later, the fallout from his outburst is still toxic, as a Tory parliamentary candidate, Nigel Hastilow, discovered to his cost last autumn when he echoed the view sometimes muttered outside polite society and stated that Enoch had been right.

Unlike the Archbishop of Canterbury speaking recently about sharia law, Powell deliberately set out to shock. But what was in his mind when he made his fateful speech in the Midland Hotel (now the Burlington) in Birmingham on the afternoon of Saturday 20 April 1968? Was it ambition, racism, or his duty as an MP to voice the concerns of his Wolverhampton constituents? Or was there something else preying on his mind?

These are the questions I set out to answer in a documentary for BBC Radio 4 in the first of a major new series of programmes recalling the momentous year of 1968.