When Ed Miliband was elected Labour leader in 2010, a delighted Neil Kinnock proclaimed: "We've got our party back." The consequent demise of New Labour produced a defeat last Thursday akin to those which Kinnock presided over.
But it is not just the sea of blue on the electoral map which is familiar from the 1980s. In Hendon, Finchley and Golders Green, and Harrow East, the brutal results of Mr Miliband's abandonment of the carefully calibrated position on Israel adopted by Tony Blair in the mid-1990s were all too evident.
Mr Blair's attack on what an aide from the time termed the party's "anti-Israelism" was not the sole reason many Jewish voters ditched their allegiance to the Tories and backed him. As a former party staffer suggests: "The politics of New Labour resonated broadly with the Jewish community."
Nonetheless, Blair also recognised that his party's stance on Israel represented a test of its seriousness about power. That test was nothing so crude as an attempt to win the support of the "Jewish vote". Instead, the former prime minister understood that the complexities of the conflict between Israel and the Palestinians bore little resemblance to the left's view of it as a simple colonial struggle between oppressors and underdogs. If Labour in government wanted to have any real influence on the conflict, it needed to abandon crude gesture politics and position itself as an honest broker.
And, for Mr Blair, Labour's position on Israel also acted as a litmus test on the hard left's wider degree of influence on the party: a lurch to the left here operated as a flashing amber light of potential problems on a range of other issues, some of which might cause more widespread electoral damage.
With Mr Miliband's departure, Labour has an opportunity to rethink. A front-runner to succeed him, Andy Burnham, is perhaps the most likely to continue his approach. When the former health secretary ran for leader in 2010, he declared himself a "friend of Israel" before adding that the "current government is making that very, very hard". Having courted the unions assiduously for the past five years, the erstwhile Blairite is not likely to challenge their anti-Israeli bent. Indeed, he followed his vote to recognise a Palestinian state last autumn by tweeting - unusually, given his responsibility for health, not foreign affairs - that the re-election of Benjamin Netanyahu in March meant "Palestine will need more international support".
A potential rival, Yvette Cooper, has never shared her husband Ed Balls's passionate Zionism and, unlike him, she backed Mr Miliband in the Palestinian statehood vote. Ms Cooper's short spell as shadow foreign secretary in 2010 also marked the start of the party's shift towards a more hostile position on Israel when she followed a visit to the Middle East with a call for mandatory labelling of settlement goods. Nonetheless, the current shadow home secretary is a pragmatist with close links to the pro-Israeli traditional right of the party.
While the likely attitude of another candidate, shadow business secretary Chuka Umunna, is unclear, he has become the pick of some centrists and is close to the party's New Labour wing.
So, too, is shadow care minister, Liz Kendall, who was the first of the candidates to declare and is already setting out an unashamedly modernising pitch. Strongly pro-Israel and less sanguine about the threat of Islamist extremism than some of her colleagues, she ignored strong-arming by the Labour whips and chose not to back her then-leader's call for Britain to unilaterally recognise a Palestinian state.
Another centrist who is set to run, education spokesman Tristram Hunt, also defied Mr Miliband and stayed away from the Palestinian statehood vote. Mr Hunt followed that defiance with a strong defence of Israel in a speech earlier this year.
The choice of Mr Miliband's successor will not be determined by where the candidates battling to succeed him stand on Israel. But the willingness of the eventual winner to pass the "Israel test" will be an early sign of how serious they are about avoiding his fate.