It tells you a lot about this majestic book, and also about its subject, that Enoch Powell leaves ministerial office on page 333, with 628 pages still to read. For the extraordinary thing about Powell is that he held office - and pretty modest office, at that - for an absurdly short period. Almost everything that is memorable about him took place after he had resigned from Harold Macmillan's government for the second time; and that was as long ago as 1963.
Not that this makes him unique. His friend and occasional cross-party ally Michael Foot was a minister (though a much more significant one) for only five years of a career spanning almost 50 years, yet he retired with the reputation of a supreme - perhaps the supreme - House of Commons man. Tony Benn held office for much longer, but it is fair to say that he will be remembered for what he did out of office rather than in it.
Unlike these two, however, Powell was a serial resigner. As number two to Peter Thorneycroft, the chancellor in Macmillan's Treasury team, he quit with his boss and his junior minister, Nigel Birch, in what Super Mac described as a "little local difficulty" but was actually the first manifestation of Thatcherite monetarism. Then, given a second chance by Macmillan (though more to keep him out of mischief on the back benches than out of regard for his indispensability), he refused to serve under Mac's chosen successor, Alec Douglas-Home, because he didn't think he was the right chap for the job.
Amazingly, the ultra-forgiving Alec Home gave Powell a third chance, but only as a junior member of his shadow cabinet after Labour's election victory in 1964. He was still a shadow minister, by this time in Heath's front-bench team, when he finally committed suicide as a serious seeker after office by making the speech that turned him into the de facto standard-bearer for the radical right inside and outside parliament.
The speech is generally known as the "rivers of blood" speech, though Simon Heffer says that Powell preferred to call it the Birmingham speech. He made it on 20 April 1968, when the shadow cabinet had just agreed a somewhat weaselly response to a government bill to outlaw racialism. The deal was, to be sure, a compromise dictated by a yawning left-right split in the parliamentary Tory party over race. But the point, in the eyes of Heath and his allies, was that Powell himself had helped to draft the compromise.
So when Powell stood up in a small upstairs room in Birmingham's Midland Hotel and delivered the fateful prophesy - "Like the Roman, I seem to see the river Tiber foaming with much blood" - he could hardly have been surprised that Heath, and more particularly his more liberal-minded colleagues in the shadow cabinet, would be outraged. Though a devoted admirer himself, Heffer concedes that his hero knew what he was doing, even if he didn't quite realise how much trouble he would cause.
So Heath sacked Powell by telephone, knowing that any delay would lead to the resignation of a substantial chunk of his front bench. Even the sacking had a Enoch-ish quality, since Powell had taken his phone off the hook, allegedly to escape the press, and an emissary had to be sent round to his house to tell him to ring Ted straight away.
The call was the beginning of one of the great personal feuds of postwar politics. Heath never spoke to Powell again. Powell, for his part, conducted eternal, Miltonic war against Ted until the moment he lost the Conservative leadership to Margaret Thatcher. It was a war conducted on many fronts besides matters of race and immigration, including passionate battles over Heath's failed attempt to control inflation by means of a statutory incomes policy and also (above all else) his successful bid to take Britain into the European Community.
The question has remained ever after: was Powell a racist? Heffer, and many others who felt they knew him well, say he definitely wasn't. I am prepared to take their word for it, not least on the book's evidence of Powell's wartime spell in and fondness for India. But if he wasn't, he was quite prepared to play on other people's racism - which in its way is actually worse. How else can one interpret the use of words such as "piccaninnies" in that speech?
Heffer records that Powell himself once explained that he didn't consciously work out things like the Birmingham text. "Decisions appear to present themselves fully dressed at the door," he explained. "There is a knock at my door, I open it, and there is a decision. And so it was with the speech." That, I fear, translates as: "Not my fault, guv'nor - I couldn't help myself."
I hesitate to add, since I shared Powell's fierce hostility to Heath's ruthless use of the party whips to take us into Europe, that I also have deep reservations about Enoch's full-blooded conversion to the anti-common market cause. For the facts suggest that Powell, once he had come to terms with the end of the British Empire, initially switched to Europe in his search for an effective role for post-imperial Britain. No doubt his passionate attachment to the concept of nationhood and the sovereignty of parliament was the crucial factor in changing his mind. But it still looks slightly fishy that his decision turned up on his doorstep just at the moment when Europe was becoming a populist cause.
Yet on one great (and oddly contemporary) issue there can be no doubt about Powell's absolute sincerity. Even if he had had no other beliefs, he believed passionately in the splendour of the British constitution, and in the concept of the crown in parliament. Even as a young soldier, he used to end his letters to his parents with the words "God save the King". His fight to save the hereditary House of Lords from a somewhat limp-wristed "reform" at the hands of Dick Crossman during the 1966 Wilson government was a model of parliamentary guerrilla warfare. But it would never have succeeded without the help of Michael Foot, who joined the battle with exactly the opposite purpose - namely, that their lordships ought to be abolished altogether, not reformed.
An only child of ambitious parents, Powell was much more than a mere swot. At Trinity, Cambridge, he became a virtual hermit, working from 5.30am to 9.30pm. He was a fellow of his college at 22, and professor of Greek at Sydney University at 25, all the while writing poetry which often reads like a melancholy parody of his mentor, A E Housman. Powell was a fierce critic of appeasement, and flew back from Australia in 1939 to join up as a private soldier. He ended the war as the youngest brigadier in the army, but without hearing a single shot fired in anger - a misfortune which cheated him of a romantic ambition to be killed in battle. He had two male friendships so intense as to raise questions over his sexuality; but he also had two heterosexual love affairs, the second with his future wife Pamela, to whom he remained devoted until his death.
But what about the book? At 1,024 pages, it would have benefited from some judicious cutting. But for all its length, it is never tedious. Heffer writes with the same lucidity as his subject, but happily without Powell's corkscrew-like sentence construction. There are good jokes, my favourite being George Brown's response, during a Commons debate, to a Powell-esque reference to the empire. "Someone shouted, 'What empire?' 'I think he means the Holborn Empire,' said George."
Finally, we learn from Heffer that Enoch Powell the classical scholar very nearly left his River Tiber phrase in the original Latin. What, one wonders, would our recent political history have looked like if he had told his tiny audience that day: Et Thybrim multo spumantem sanguine cerno?