For as long as anyone cares to remember, the lay leaders of British Jewry's major organisations have observed an unwritten code: to avoid public criticism of Israel.
On rare instances, the Board of Deputies might have raised its voice, such as over the Sabra-Shatila massacre of 1982. But by and large, if they had qualms about Israeli policy, community leaders have preferred to convey them privately to Israel behind closed doors.
Some rabbis, it is true, may have claimed prophetic licence to speak out - most notably Chief Rabbi Lord Jakobovits, a critic of West Bank settlement, who warned in 1991 that trying to rule over the Palestinians would lead to "the destruction of Judaism".
But his successor, Lord Sacks, has shown a marked reluctance to enter controversy over Israel; and when eight years ago he told the Guardian that he felt "uncomfortable" about some events in Israel, a delegation of lay leaders left him in no doubt that his candour had been a mistake.
In baring his concerns about the direction of Israel so openly at the weekend, Mick Davis has torpedoed that code of silence. So why his intervention now - beyond his palpable frustration at Israel's political leadership?
The survey published in July by the Institute for Jewish Policy Research suggests a changing Zionist landscape. More than a third of respondents felt that Israel bore at least equal responsibility to that of its adversaries for the impasse in the Middle East.
More than 40 per cent thought that Israel did have a choice over whether to launch military action.
These figures are far higher than would have been likely in the halcyon days of 1967, when British Jews would have generally blamed Arab rejectionism for lack of peace,while accepting the doctrine of ein breira, [there is no choice], that Israel had no option when sending troops into battle.
More than half in the JPR survey - 55 per cent - saw Israel as an "occupying power" in the West Bank (rather than as liberator of Judea and Samaria). A significant body of British Jews therefore seems to have no problem coupling affinity with Israel with a critical approach to the policies of its government.
Nor could leaders ignore the growing impetus to set up a doveish Israel campaign group here, similar to the American J Street.
Abroad, too, dissent has chipped away at the default position that the diaspora's duty is unconditional defence of Israel. Professor Steven Cohen, an expert on Israel-diaspora relations, recently observed that there were young American Jewish activists who although "highly engaged" with Israel, nevertheless resisted the label "pro-Israel", because they associated it with support for policies they saw as "misguided, mistaken and sometimes immoral".
His observations contain an implicit warning. If Jewish leaders do not move with the times, young people may desert the Jewish mainstream altogether.
The question is what happens next. It is clear that Mr Davis is no maverick and that his views are shared by a significant number of others in the inner circles of British Jewry's decision-makers.
But the habits of consensus die hard. There will be pressure on members of the JLC to put a lid on any debate - and their consciences back in the box.
The argument will be made that whatever their views, these are better communicated to Israel through discreet diplomacy than public statements.
But, in a way, the cat is out of the bag. Thanks to Mr Davis's openness, the Jewish public has a better insight into what some of its leaders really think, and that will colour perceptions of their actions in future.
Even if nothing else happens, those planning a UK J Street will feel emboldened that they are on the right track.