His reason was simple. As a Jew, he no longer felt comfortable in a party he had joined when Clement Attlee was its leader. There were too many hotheads lurking in its nooks and crannies spouting vile anti-Semitic abuse.
He’s gone now, and though I regret his passing, I’m glad – in a way – that he’s no longer around to see what the party he had campaigned for all his adult life has become because he would not only have been saddened, but incandescent with rage.
Anti-Semitism wasn’t an abstract issue for him, the rantings and hatreds on social media, the crude stereotyping, the crazed idiocy about shadowy international conspiracies headed by Jews.
This was a man who had fought through Holland towards the German border in the closing months of the Second World War, perfectly aware that if he had been captured and identified as Jewish, his fate would likely have been infinitely more grim than other prisoners of war.
Hard though it is to credit, Labour’s anti-Semitism problem has become worse since he resigned, to the extent – as revealed by this newspaper – that an MP, Chris Williamson, could stand up at a meeting in Sheffield and be applauded for saying the party was too apologetic about the issue.
How infected the party has become by anti-Semitism was further underlined at the weekend when the Liverpool Wavertree MP Luciana Berger revealed the extent of the abuse that made her quit Labour. She’s not alone. Enfield North MP Joan Ryan made similar disclosures about the hate mail she has received.
The revelations were so disgusting that they’re not fit to be repeated. The language spat would not have sounded out of place from a member of the Nazi party in the mid-1930s.
So too reports that senior Labour officials opposed recommendations to suspend members accused of anti-Semitism show a party in which this horrible subculture has been allowed to flourish.
It is all very well deputy leader Tom Watson now taking a firm stance about anti-Semitism, and Lord Falconer being appointed to head an internal review, but it all smacks of coming far too late.
Jeremy Corbyn has done nothing like enough to address the problem, which has grown on his watch. No other Labour leader since Attlee would have tolerated the shameful descent of the party into this hateful state.
And there appears to be a direct link between the growth of anti-Semitism and Mr Corbyn’s most fervent supporters on the left, where animosity towards Israel has mutated into hostility towards Jews in general. That has only been intensified by Mr Corbyn’s long-standing links to groups for whom Israel is a sworn enemy.
Lord Falconer was correct in his assertion at the weekend that the British people will not trust Mr Corbyn as Prime Minister as long as his party is tainted by anti-Semitism.
He should have gone further – Mr Corbyn is not fit to be Premier because of his inaction in stamping it out.
His statements on the issue have been equivocal at best, too often couched in a vague condemnation of racism in general, when they should have been clear that anti-Semitism is a specific prejudice that has taken root in local parties.
Any internet search for the terms Labour and Jews soon throws up some especially nasty stuff.
Unthinkable though it would have been only a few years ago, the party of Attlee, Wilson and Blair, one which historically set its face against prejudice and bigotry, is now firmly linked to anti-Semitism on the world’s primary source of information. Breaking that link will be especially difficult and time-consuming.
Words from Watson and Falconer are not enough. The people who applaud apologists for anti-Semitism need to be kicked out of the party before they poison its soul still further.
Labour must undertake widespread expulsions of members to rid itself of this cancer, and make it clear that anti-Semitism will not be tolerated under any circumstances.
But there needs to be another step. It is time that the police were called in to investigate anti-Semitism as a hate crime. Those responsible deserve to be arrested, questioned and – if the abuse hurled at Ms Berger and others reaches the necessary legal threshold – prosecuted.
If the degree of hatred being levelled at Jews was to be directed instead at the Muslim community, there would – quite rightly – be an outcry amongst Labour members and demands that those responsible face sanction.
Every moderate Labour member I know is deeply distressed by this taint on their party, and some are furious that it has become home to peddlers of hatred, which is what the anti-Semites are.
This is an existential crisis for Labour. Unless the party tackles it head-on, making it clear that the anti-Semites are its enemies, the electorate will turn away in revulsion.