The visit to Britain by President Isaac Herzog of Israel is a moment to mark the sorry state of affairs that now preside in the nation of Benjamin Disraeli and Winston Churchill. Mr. Herzog is making the journey from Jerusalem ostensibly to buck up the country’s Jewish community, which has been beset, like Jews throughout Europe, with a staggering wave of antisemitism. One recent poll discloses that half of Britons harbor antisemitic attitudes.

Britain’s leaders offer studies in waffling. Prime Minister Keir Starmer initially appeared devoted to flushing out the Labor Party toxins that thrived under Jeremy Corbyn. He has of late, though, wheeled on the Jewish state, and now threatens Israel with recognition of a Palestinian Arab state if Jerusalem does not do London’s bidding. That threat comes even as Britain’s outgoing foreign minister, David Lammy, acknowledges that there is no genocide in Gaza.

Mr. Starmer is set to meet Mr. Herzog on Wednesday, and the premier appears primed to deliver a tongue lashing to the president over Gaza and, now, Israel’s strike on Hamas’s leadership in Qatar. No. 10 says in a statement that on the agenda will be the “intolerable situation in Gaza” and the “action Israel must take to end the horrific suffering we’re witnessing.” That hardly sounds like a red carpet invitation to High Tea.

For some English parliamentarians, even Mr. Starmer’s chilly reception is too much. Some 60 members of Parliament called upon Her Majesty’s Government to block Mr. Herzog from setting foot on British soil. Pro-Palestinian voices are calling for Mr. Herzog to be arrested. If Prime Minister Benjamin Netanyahu or the erstwhile defense minister, Yoav Gallant, were to visit England their arrest would be mandated by the country’s signatory to the Rome Statute, the charter of the International Criminal Court. That tribunal has issued warrants on the allegation of genocide.

Like the flailing leaders of France and Spain, Mr. Starmer’s government appears to be grandstanding on Gaza to deodorize domestic failure. That and, perhaps, kowtowing to a restive alliance between the hard-left and Islamist. A new party, “Your Party,” is emerging, led by none other than Mr. Corbyn and another leftist, Zara Sultanah. Ms. Sultanah has pronounced that “Labor is dead,” and she and Mr. Corbyn have nothing save contempt for Sir Keir.

If only Mr. Starmer’s hostility to Mr. Herzog could be solely attributable to the president’s familial history. The president’s grandfather, Rabbi Yitzhak Halevi Herzog, moved to Leeds from Poland and then on to Belfast, eventually becoming the chief rabbi of the Emerald Isle. Herzog learnt Irish and so devoted himself to the cause of Éirinn that he became known as “the Sinn Féin Rabbi.” He supported Irish independence from British rule.

Rabbi Herzog’s enthusiasm for both the Irish Republican Army and the Irgun of Vladimir Jabotinsky and Menachem Begin meant that he was a foe of England twice over. In 1939, after becoming chief rabbi of Mandate Palestine, he stood on the steps of an ancient synagogue at Jerusalem and ripped in two a copy of the British White Paper, which barred Jewish emigration to Palestine. That policy doubled as a death warrant for European Jews.

Rabbi Herzog’s son Chaim, raised primarily at Dublin, became president of Israel. In 1975, as ambassador to the United Nations, he mimicked his father’s gesture, tearing asunder the resolution equating Zionism with racism. Now his son is striding into 10 Downing Street with knees unbent. One imagines that the old warriors of the Irgun — and the IRA — would be proud of the derring-do of the country over which Mr. Herzog presides.