Ralph Miliband, father of the Labour leadership rivals David and Ed, is remembered as a great teacher and an inspiration to young socialists. So which son is his true heir?

During a recent televised debate, the five candidates for the leadership of the Labour Party were asked to name their "Labour political heroes". Diane Abbott and Andy Burnham both chose John Smith, Tony Blair's predecessor as party leader. Ed Balls's implausible choice was Blair, and Ed Miliband chose the architect of Labour's first election landslide, Clement Attlee. But by far the most interesting nomination was David Miliband's: his Labour hero, he said, is Anthony Crosland, the author of The Future of Socialism (1956) and the leading theoretician of postwar social democracy.

It's an intriguing choice because, as his bro­ther, Ed, acknowledged in a lecture in 2006 on the 50th anniversary of the publication of The Future of Socialism, "in the household in which [we were] brought up, Crosland and his ideas were not popular - his critique of Marxism, his views on public ownership". The Milibands' father, Ralph, a Marxist intellectual who died in 1994, spent much of his working life warning his comrades on the left not to be seduced by "siren" voices such as Crosland's.

“It's a great irony that people are saying of David and Ed that they are the inheritors of Croslandism in the Labour Party," says Leo Panitch, who studied under Ralph Miliband at the London School of Economics in the 1960s and later co-edited the annual journal Socialist Register with his former supervisor. "Ralph's finest book, The State in Capitalist Society [1969], was written very consciously as a critique of Crosland's position.

“Crosland believed that Marxism was no longer relevant, because the state had detached itself from the influence and control of the capitalists. But Ralph set out to show that the state was not independent of the capitalist class."

Miliband remained locked in intellectual combat with the kind of revisionist social democracy represented by Crosland for the rest of his life. His final book, Socialism for a Sceptical Age, completed shortly before his death, begins by disparaging "mild social democracy" as an "adaptation" to capitalism, not an alternative to it (for him, socialism was a "fundamental recasting of the social order" or it was nothing). And he dismisses Crosland's Future of Socialism, in a footnote, as the "bible of Labour 'revisionism'".

In the acknowledgements, Miliband thanks his sons for their "very helpful (and stringent) criticisms" of early drafts. I asked David what those criticisms were. "They were about the way the world is changing," he said - an impeccably Croslandite answer since, as Ed pointed out in his lecture, Crosland's revisionism partly consisted in a "determination to see the world as it is", not as socialists or social democrats think it ought to be.

Both brothers, Panitch says, "were pushing Ralph to make socialism sound more possible or plausible. And he was listening to them. Ralph was very proud of how seriously they were taking politics." Proud despite his view that, as he put it in the 1976 edition of the Socialist Register, "the belief in the effective transformation of the Labour Party into an instrument of socialist policies is the most crippling of all illusions to which socialists in Britain have been prone" - although it was an illusion to which even he had intermittently succumbed, and would again in the 1980s.

Ralph Miliband joined the Labour Party in 1951, having fled Belgium for Britain in 1940. He was born in Brussels in 1924 to Polish-­Jewish parents. In notes for a "political autobiography" that he never published, he wrote: "The political climate in our house was generally and loosely left: it was unthinkable that a Jew, our sort of Jew, the artisan Jewish worker, self-employed, poor, Yiddish-speaking, unassimilated, non-religious, could be anything but socialistic."

In 1939, aged 15, he joined Hashomer Hatzair, a left-wing Zionist group. A year later, living in London with his father (his mother and sister spent the war in Belgium, sheltered from the Nazis by a farmer and his family), he made a pilgrimage to Marx's grave in Highgate Cemetery. He wrote of "standing in front of the grave, fist clenched, and swearing my own private oath that I would be faithful to the workers' cause. I do not recall the exact formulation, but I have no doubt of the gist of it; and I thought of myself as a revolutionary socialist or communist . . ."

Yet Miliband was never tempted to join the Communist Party, which set him apart from other leading intellectuals of the British "new left" that emerged following the Soviet invasion of Hungary in 1956. Michael Newman, in his biography Ralph Miliband and the Politics of the New Left (2002), says he went through a brief Leninist phase as an adolescent, but that he "moved away from that - you see signs of his shift away from [seeing] the Soviet Union as a kind of beacon early, in the 1940s. A long time before Hungary, in other words. He was someone who never had uncritical enthusiasms."

Into Labour

Instead, under the influence of Harold Laski, who helped get him an assistant lectureship in political science at the London School of Economics in 1949, Miliband gravitated towards Labour, specifically the Labour left, whose de facto leader in the early 1950s was Aneurin Bevan. By the time Bevan died in 1960, Miliband was preparing to leave the party, having concluded that it was no longer worth working with the Bevanites, who, he thought, had reconciled themselves prematurely with the revisionist leadership of Hugh Gaitskell.

His first book, Parliamentary Socialism: a Study in the Politics of Labour, published in 1961, is a record of this growing disillusionment with the party. It is also an anatomy of the culture of "Labourism", his term for Labour's historic and debilitating attachment to the institutions of the British state - to the first-past-the-post electoral system and the idea that left-of-centre politics begins and ends with the capture of the levers of power in Westminster.

Miliband finished writing the book in 1960, at the height of the internecine warfare between the Gaitskellite "revisionists" (including Crosland) and an "unstable coalition of their opponents in the Labour Party and the trade unions". And for all his dismay at Bevan's reconciliation with Gaitskell after 1956, when the former was appointed shadow foreign secretary, Miliband ended Parliamentary Socialism by keeping open the possibility that Labour might one day become in deed the kind of socialist party that it had always been in word.

However, the disappointments of the Wilson government of 1964-70 led him to a much more pessimistic assessment of the likelihood of Labour ever being transformed into an "instrument of socialist change". In the postscript to the second edition of Parliamentary Socialism, published in 1972, Miliband concluded that Labour would remain what, in his view, it had always been: "a party of modest social reform in a capitalist system within whose confines it is ever more firmly and by now irrevocably rooted". Nevertheless, he gave short shrift to the view that there is no essential difference between a liberal, constitutional capitalist regime and a fascist one. That, he argued, is merely the obverse of the Labourist fallacy that the election of a social-democratic government is sufficient to change the "nature and role of the state" for ever.

He was similarly sober in his response to the unrest among students and staff at the LSE in the late 1960s. While he formed the Council for Academic Freedom and Democracy with a colleague, John Griffith, in response to the expulsion of several lecturers, he was not, Panitch says, "uncritical of the ultra-leftism of some of the students". One of the forums in which Miliband developed his criticisms was an informal seminar on "Problems of Contemporary Socialism". "It was marvellous," Panitch remembers. "He would bring together very high-powered young intellectuals and guests.

“The first time I ever laid eyes on Noam Chomsky was in that seminar. There was a debate between Chomsky and Eric Hobsbawm over the Spanish civil war."

Panitch introduced Miliband to Tony Benn, whom Miliband had come to regard as a more "resilient" champion than the Labour left had had at any time since Bevan. By the early 1980s, he was ready to admit that he had underestimated how substantial a challenge the new generation of left-wing activists inside Labour would pose to the party leadership. Whereas, only a few years earlier, Miliband had believed that the condition of socialist renewal in this country was the formation of a new party, now he was altogether more optimistic about the prospects of conquering Labour for socialism.

The task for left-wing intellectuals, he thought, was to figure out what the programme of a "socialist Labour Party" would be like. To this end, he instigated an informal discussion group, the Independent Left Corresponding Society, which met every Sunday evening at Benn's house in Holland Park, and included the New Left Review editor, Perry Anderson; the economist Andrew Glyn; the socialist historian Robin Blackburn; and other Labour MPs, including Jeremy Corbyn. "Ralph felt there needed to be a proper Labour Party," Benn recalls. "He was a very good analyst and a very good teacher. And he had a great deal of charm."

Enduring vision

Blackburn compares the activities of the group to those of a think tank. "It had a very practical orientation; it wasn't a purely theoretical exercise. It was charting a different course for the left and Ralph was the main inspiration."

They published pamphlets on a range of issues, including electoral reform, to which Miliband was an early convert. (By the end of his life, he was arguing that an ideal electoral system would lie somewhere between first-past-the-post and strict PR, a position close to the one now adopted by his sons, both of whom are supporters of the Alternative Vote system.)

Miliband hugely overestimated the strength and longevity of the Bennite insurgency, which had fizzled out by the second half of the 1980s, despite the Chesterfield Conferences that he helped to organise in Benn's constituency. But what endures from this last phase of his career is not policy prescriptions so much as a vision of what democratic-socialist politics might be. In the penultimate sentence of his final book, which Ed told me is his favourite of any of his father's work, Miliband wrote: "In all countries, there are people, in numbers large or small, who are moved by the vision of a new social order in which democracy, egalitarianism and co-operation - the essential values of socialism - would be the prevailing principles of social organisation."

Jonathan Derbyshire is culture editor of the NS

Ralph Miliband: CV

1924 Born Adolphe Miliband to Polish-Jewish parents in Brussels, Belgium
1940 Flees to England with his father
1941 Begins degree at the London School of Economics
1947 Graduates with a First after wartime service as a navy intelligence officer
1949 Appointed assistant lecturer in political science at the LSE
1951 Joins the Labour Party
1961 Marries the Polish-born Marion Kozak. Parliamentary Socialism is published
1964 Co-founds the Socialist Register
1965 First son, David, is born
1969 Second son, Edward, arrives. The State in Capitalist Society is published
1972 Takes chair in politics at the University of Leeds
1978 Leaves Leeds post and takes up a series of part-time teaching jobs in the United States and Canada
1981 Helps found the Socialist Society
1994 Dies aged 70