His remains rest under the watchful eye of Karl Marx.
In a corner of Highgate cemetery in north London, 12 yards or so from Marx's famous statue and tomb, lies a small square stone. "Writer Teacher Socialist" reads the simple inscription.
Ralph Miliband was one of Britain's foremost political theoreticians, an academic of world renown. And he was proud to proclaim himself a Marxist.
He died in 1994, a few weeks before Tony Blair took over the Labour Party.
By then he could see, with great unease, both his sons embarking on careers within what soon become known as New Labour - David advising Tony Blair, and Ed in the other camp, working for Gordon Brown.
Ralph Miliband was not a Marxist in the Marxist-Leninist sense. He was no fan of the Soviet dictatorships and one-party states. Nor did he believe in violent revolution to overthrow capitalism.
In crude terms he was neither a Stalinist nor a Trot. Yet he was deeply sceptical about whether Parliament would ever do much to emancipate the working class.
Miliband was convinced instead that progress would depend on activity outside Parliament, through trade unions and other protest groups liberating themselves through radical activity.
Working closely with other academics, Miliband was a leading figure in what became known as the New Left. He co-edited the annual journal Socialist Register.
But, although Miliband briefly belonged to Labour in the 1950s (and even addressed its conference in 1955), he had little respect for the party which one of his sons is about to lead.
Labour, he thought, would always give in to international capital, and enslave itself to US foreign policy.
His friend, writer Tariq Ali, recalls one conversation he had with Ralph about the brothers' involvement in the party.
"I remember one occasion when Ralph rang me up and said, 'By the way did you listen to that speech Neil Kinnock made yesterday?' And I said I did.
"He said, 'What did you think of it?' I said 'Just empty waffle - real nonsense, Ralph.' And he burst out laughing. He said, 'I think young David wrote that speech!'"
Ralph Miliband was a Jewish refugee from the Holocaust. Originally born in Poland, he was living in Belgium when the Nazis invaded in 1940, and he and his father Sam escaped on the last boat from Ostend.
In England he studied at the London School of Economics (LSE), and soon got an academic job there under his mentor Harold Laski, a Marxist who served as Labour Party chairman just after the war.
In 1965, the year David was born, Ralph Miliband bought a house in Edis Street in London's Primrose Hill, not far from Euston station. David Miliband still lives in the house today.
Edis Street became one of the great London meeting places for Marxists and socialists from around the world. The family's basement dining room was open house, and the scene of high-minded and often heated discussions between major figures on the Left.
"The key thing about the Miliband household was this belief in argument and debate as the way to arrive at the truth - or to search for the truth," recalls socialist and friend of Ralph, Hilary Wainwright.
The boys were immersed in all this, and began contributing from a precociously early age.
"[They were] very, very fresh lively, intelligent and I must admit Ed amazed me by being able to do the Rubik's Cube... in one minute 20 seconds and, as I recall, just with one hand too," remembers socialist academic Robin Blackburn, another close friend of Ralph's.
And yet it's hard to pinpoint exactly what the boys inherited from their dad - apart from a love of politics, a relish for debate, good contacts and a shared commitment to electoral reform.
In fact, several people who know the family reckon that their mother, Marion Kozak - who still uses her maiden name - was a bigger influence on their development than Ralph.
"Marion has a crusading spirit - a really campaigning spirit. She is someone who will always be involved in issues - international political issues or local political issues," says Dr Marc Stears, politics fellow at the University of Oxford.
"And that energy really was infectious, and there's no doubt that Ed got a lot of his drive from Marion and a lot of his feel for nitty-gritty grassroots politics from Marion too."
She too escaped the Holocaust and met Ralph while a student of his at the LSE.
An early activist in CND, Marion has campaigned locally for nursery schools, and for human rights overseas, and is a leading member of the Jews for Justice for Palestinians group. But unlike Ralph she still belongs to the Labour Party, though she, too, is well to the left of David or Ed.
Her friends say the contest between the boys this summer has been a huge "strain" for Marion. She has even told people it would have been much easier had they simply become academics rather than politicians.
It's an astonishing situation. Miliband is a rare name in Britain, and the only two men with it are competing for the leadership of the same party.
Robin Blackburn believes their father would have been pleased by what his sons have achieved - and yet horrified at the same time.
"On the one hand I think he would have been very proud and amazed - on the other hand I think he would have been appalled by the politics of Labour, and it should be said even the politics of this Labour leadership contest at the moment, which seems to be completely bereft of ideas or direction," he says.
In a lifetime teaching at the LSE, at Leeds University and in America, Ralph Miliband built up a loyal following of former students who were inspired by his teaching.
Yet Mr Blackburn says, with some irony, that neither son can be classed as a Milibandite.
And one can't help suspecting that in Highgate Cemetery this weekend, around 5pm when the leadership result is declared, a small bit of soil will be quietly disturbed.
Watch Michael Crick's film on Ralph Miliband and his sons on Thursday, 23 September 2010 at 2230 BST on BBC Two, then afterwards on the Newsnight website.