Enoch Powell is one of the strangest figures in British political history. While most of his contemporaries – he lived from 1912-98 – have faded from public memory, he endures like an angular building, erected in a prominent spot and faced in encaustic tiles, never mellowing.

“Some loved him, some hated him and some thought he was mad,” as Michael Cockerell remarked in an admirable radio piece about him after his death, “and the three groups were not mutually exclusive.”

His critics have helped to keep Powell’s name alive. They denounced the BBC for last Sunday broadcasting in its entirety his inflammatory “Rivers of Blood” speech, delivered 50 years ago this Friday.

By uttering these protests, they paid him a kind of unintended compliment. Powell, they seemed to imply, was still dangerous, still able to stir up racial hatred, still a man who in the interests of public safety must be suppressed rather than given a hearing.

And yet the greatest danger Powell posed at the height of his powers was to himself, and to his own party, the Conservatives. For by launching the most notorious assault on immigration ever uttered by a British politician, he left the unhappy impression that there was no place for immigrants in the Conservative Party.

They might be natural conservatives, devoted to family, religion, hard work, the Queen and cricket, who came to Britain because they admired the British tradition of freedom under the law, yet they were driven towards Labour, which was more ready to welcome them into British politics. This is all the odder when one considers that it was the Conservatives who in Benjamin Disraeli, grandson of an immigrant from Italy, provided this country’s first and so far only Prime Minister of Jewish descent, and made the him the object of a posthumous cult, the Primrose League, which at its height had almost two million members.

Powell formed an unduly rigid idea of Britishness. In old age he was still asking Cockerell, who made a wonderful film about him: “What’s wrong with racism? Racism is the basis of nationality.”

Cockerell had already brought tears to Powell’s eyes, by getting him to read a poem inspired by the first woman with whom he fell in love, who rejected him.

We could see that Powell is a man of deep emotion. His brusqueness, for he could be appallingly rude, was a way of protecting himself. Like many quarrelsome people, he wished to conceal from the outside world how vulnerable he was.

From his earliest years, we find Powell erecting a kind of intellectual armour. John Enoch Powell, born in June 1912 in a house overlooking a railway cutting in Stechford, Birmingham, was an only child, his father the headmaster of a primary school, while his mother, who was also a teacher, gave up her profession and taught herself Greek in order to teach it to her son.

At the age of three, they nicknamed him the Professor, because of the lectures he liked to give to visitors about the stuffed birds shot by his grandfather. In some respects he was to remain throughout his life the Professor, the scholarship boy who knew better than anyone else the right answer, and therefore had the right to lay down the law to his contemporaries. It is hard to think of anyone has who played the game of oneupmanship with more single-minded intensity.

He won a place at King Edward’s School, Birmingham, and travelled there on the same train as Denis Hills (later to spring to fame as a captive of Idi Amin), who recalled:

“His penetrating blue eyes, furrowed brow and set mouth discouraged familiarity, and he was reputed to be cleverer than any of the masters. He didn’t play games but was sometimes caught up in the the train scrums where we behaved like savages.”

Powell admitted he had unscrewed luggage racks and thrown them out of the window in tunnels. Hills related much worse exploits than that, though without implicating Powell. But one may still posit, as in many Tories, a submerged vein of anarchy. Authority was required to avert savagery.

In Powell’s case, he buried himself in extraordinarily hard work, and achieved brilliant results. He won a scholarship in classics to Trinity College, Cambridge, where his custom was to rise at five in the morning, wrap his body in an overcoat and his feet in a blanket (for he supposed he would concentrate better in the cold), and work. He had no social life whatever, a limitation which may later have proved a handicap, and became a disciple of Housman, in whose manner he wrote poetry, and, more worryingly, of Nietzsche.

He took a starred first, became a fellow of his college, and at the age of 25, to his regret a year later than Nietzsche, a Professor of Classics at Sydney, in Australia.

These triumphs were brought to an end by the Second World War. Powell returned home and joined up as a private in the Royal Warwicks. He was seen to be prodigiously bright, was transferred to intelligence duties, took on the task of reading Rommel’s mind in North Africa, and by the end of the war had completed, as a brigadier serving in India, a second meteoric career.

He fell in love with India and conceived the ambition of becoming Viceroy, so came home in order to enter politics at Westminster, the necessary route to that magnificent office. He began by serving with Iain Macleod and Reggie Maudling in the Conservative Research Department, under the leadership of Rab Butler, and in 1950 was elected with a majority of 691 votes Member of Parliament for Wolverhampton South West.

The Indian Empire was already no more, but Powell accepted that fact, and fell in love with the House of Commons. He was very soon offered junior ministerial office, at first refused but then accepted it, in 1957 became Financial Secretary to the Treasury, and in 1958 resigned along with his Treasury colleagues, Peter Thorneycroft and Nigel Birch, in protest at the profligacy of the Prime Minister, Harold Macmillan.

Here was the stern, unbending side of Powell, a politician who espoused control of the money supply, and free-market economics, 20 years before Margaret Thatcher, who later acknowledged her debt to him, and expressed her admiration for his “impeccable and implacable” reasoning. He entered the Cabinet as Minister of Health in 1960, but along with Macleod refused to serve under Macmillan’s successor, Sir Alec Douglas-Home, for the two of them, friends since their days in the Conservative Research Department, were convinced that their old chief, Rab Butler, should have become Prime Minister.

Douglas-Home lost the general election of 1964 by four seats. “Had those two pulled their weight,” he later wrote of Macleod and Powell, “I have no doubt at all that our short-head defeat would have been converted into a narrow victory.”

Edward Heath won the race to succeed Douglas-Home, receiving 150 votes to 133 for Maudling and 15 for Powell. But Powell was still a mainstream figure, and a potential future leader, and asked for and got the shadow Defence portfolio.  In so far as he was identified with a cause at the time, it was with free market economics.  It became his most successful – eventually being taken up by the Thatcher goverments and, in essence, continued under the Blair ones, and to this day.

In April 1968, he threw away that mainstream status by giving the Rivers of Blood speech. He had not warned Heath of what he was going to say, and could not supply the evidence to support some of the more lurid anecdotes which he told about the complaints of his constituents against immigrants.

Powell said he had a duty to raise his constituents’ concerns, and to warn that the country was undergoing an unwanted and irreversible change which would lead to race riots as severe as were then occurring in America. It seems clear, however, that although he wished to make a nuisance of himself, he did not intend to be sacked by Heath, which was what happened.

William Rees-Mogg, editor of The Times, condemned “an evil speech”, said this was “the first time that a serious British politician has appealed to racial hatred in this direct way way in our post-war history”, and supported what the Conservative leader had done: “In dismissing Mr Powell Mr Heath takes the known risk of having Mr Powell as an enemy; that, fortunately, is less grave than the risk of having Mr Powell as a colleague.”

A majority of moderate Conservatives supported Heath. Bill Deedes and many others complained that by using such intemperate language, Powell had made it impossible for decades afterwards for Conservatives to discuss immigration in a sensible and measured tone.

A sensible and measured tone did not come easily to Powell. He was a man who craved certainty, and was more inclined to believe he had attained it if he paid the price of incurring the lasting enmity of his opponents. He nevertheless stayed within the Conservative Party, and in the general election of 1970 was returned with a record majority of 14,467 for Wolverhampton South West.

Thanks in part to the strong Conservative performance in the West Midlands, Heath became Prime Minister – a result which meant Powell was unlikely ever to return to the Cabinet.

Powell had nevertheless struck a chord with his Rivers of Blood speech. For several decades after he delivered it, one could enter any downmarket pub in the land and find people who declared “Enoch was right”.

But that just showed his opponents how wrong he had been. By stirring up such emotions, he had been playing with fire. To them, he had behaved in an unforgivably racist and rabble-rousing way.

Powell was unrepentant. He found in the defence of the British nation and Parliament his great new cause. As he himself put it, “The sleeping nation will not be wakened by lullabies.”

He conducted a fierce but failed resistance to Heath’s campaign to take Britain into the Common Market, as it was then known. For Powell, this meant the abandonment of self-government, which was tantamount to national suicide. He was absolute in defence of parliamentary sovereignty, and would not concede that his fears might be overblown.

Like Joe Chamberlain at the end of the 19th and start of the 20th century, Powell was an instinctive Unionist who made the political weather, and heavy weather it was too. He wanted to rouse the nation from its torpor, for as he himself put it, “The English as a nation have their own peculiar faults. One of them is that strange passivity in the face of danger or absurdity or provocation.”

He saw the importance of the idea we have of ourselves, for “the life of nations, no less than that of men, is lived largely in the imagination”. According to him, the Commons is “the personification of the people of Britain”, so any loss of power to Europe was a disaster.

He therefore fought and lost a remorseless battle against Heath’s plan to enter the Common Market. In the general election of February 1974, he went so far as to stand down from his seat and urge people to vote Labour, in order to get a referendum on the European issue. Heath very narrowly lost that election, so Powell had taken a kind of revenge on him.

A heckler accused Powell of being Judas, to which Powell retorted: “Judas was paid! I am making a sacrifice!” Here was deep emotion. Powell was an orator of mesmeric power in part because his audiences could tell he felt so deeply the truth of what he was saying.

His wife, Pamela Powell, saw what a loveable man he was behind his carapace of harsh certainties. She was a colonel’s daughter and had been his secretary in the Conservative Research Department. She was entirely loyal to him, and he to her. Each year, on their wedding anniversary, he would write a poem for her, and present her with a rose for each year of their marriage.

So Powell was a romantic, but one who, on the subject of immigration, made grotesque errors of taste and judgement, and was then too stubborn to admit that he had erred. The clarity of his mind prevented him from appreciating the messy realities of Britishness, or tolerating the charitable hypocrisies which this form of nationalism can entail.

His wife told him “his principles got in the way half the time”, as she put it in an interview for the valuable book Enoch at 100, published in 2012, 14 years after his death. I was fortunate enough to meet her at a lunch given by Lord Lexden for her and Mary Wilson, the widow of Harold Wilson. The two women were delightful, got on well with each other, and made one think the better of their husbands. Pamela Powell took the chance to ask after family friends who had broken off all contact with the Powells after the Rivers of Blood speech.

At the second general election of 1974, Powell was invited by the Ulster Unionists to stand for South Down, a seat he held until 1987. Here were comrades as unflinching as himself, and he obtained for Ulster a larger and fairer allocation of parliamentary seats.

Even his critics would admit that Powell was, in his way, one of the great parliamentarians of the 20th century. His speech delivered at 1.15 a.m. on 27 July 1959, in which he condemned his own government for attempting to cover up the Hola Camp massacre in Kenya, was described by Denis Healey as “the greatest parliamentary speech I ever heard”, with “all the moral passion and rhetorical force of Demosthenes”.

For better and worse, Powell liked to push his arguments far beyond the usual boundaries of politeness, temperance and party loyalty, which is one reason why he has attained no settled place in history. Few politicians have ever thought and felt so deeply about the British nation, but his claim that allowing so many immigrants into the country was “like watching a nation busily engaged in heaping up its own funeral pyre” now sounds hysterically intolerant, and has not been vindicated by events.