The decisions taken yesterday by Britain’s Trade Union Congress (TUC) on the subject of Palestine mark the end of an era.

Just a few years ago, the TUC was electing people like Roger Lyons, the head of Trade Union Friends of Israel (TUFI), as its President. Lyons was followed as TUC president by Michael Leahy, a founder of Trade Unions Linking Israel and Palestine (TULIP). When pro-Palestinian campaigners tried to bring up the question of support for a boycott of Israel or the Histadrut, they were shunted aside. TUC General Secretary Brendan Barber played a leading role as a force for moderation in the global trade union movement.

Today, things are completely different.

Yesterday, the TUC at its annual conference passed the most anti-Israel resolution in its history.

It denounced Israel for the attack on Gaza without a word about the Hamas missile strikes which targetted Israeli civilians, or the use of human shields by the terrorist organization.

It called on the UK “to end immediately arms trading with Israel including all military-industrial collaboration. The TUC should, working with the relevant unions, press those companies involved in supporting Israel’s military to cease to do so.”

This statement went even further than the one put out earlier by Amnesty International which at least called “on the UN to immediately impose a comprehensive arms embargo on Israel, Hamas and Palestinian armed groups.”

It called for “the suspension of the EU-Israel Association Agreement until the rights of the Palestinians are established”. (It’s not clear which rights the TUC is referring to — and this could include the “right of return”.)

The TUC called for its “affiliated unions to consider strategies – such as worker capital strategies including pension funds – to put pressure on complicit corporations to cease to do so and withdraw from the Occupied Territories.”

It called for all its member unions to affiliate to the pro-Hamas Palestine Solidarity Campaign (PSC), even though that Campaign, unlike the TUC itself, is not committed to supporting a two-state solution. Its logo shows all of Palestine united as a single state.

And the resolution it committed the TUC — which previously played a moderating role in the international labour movement — to push for unions in Europe and around the world to adopt similar policies. As the TUC has considerable influence in the global labour movement, this could be the most significant thing the resolution actually said.

One cannot overstate the importance of this change.

Britain’s trade unions, which historically tried to bridge the gap between Israelis and Palestinians, and which saw themselves as being “pro-peace” have now taken sides. They no longer bring over representatives of the Histadrut and Palestinian trade unions to British union conferences. Instead, they are on the side of the Palestinians, as they see it, demanding ‘free Gaza’ and ‘Justice for Palestine’ — and they have burned their bridges to the Jewish state and its trade union movement.

And let’s not forget that the TUC stands at the top of the largest voluntary membership organization in Britain — representing 54 unions with 6.2 million members.

Why has this happened?

It’s not simply that groups like the PSC have campaigned effectively — though they have.

Nor is it the fact that Israel’s gotten some pretty bad press in recent weeks (and years).

There’s also the question of whether moderates in British unions could have done something different. Because there is no question that they have failed, and failed completely, to stem the pro-Hamas tide.

The days when a group like Trade Union Friends of Israel could hold a fringe meeting at a TUC event, serving little pitas, hummus and glasses of Israeli wine, attended by the Israeli ambassador and the TUC’s General Secretary, are gone.

It’s not because TUFI has done the wrong things. It’s because the Jewish community and others who support a more moderate stand in the unions have abandoned the field, and given up the fight.

A couple of years ago, the British Jewish community held an enormous event attended by thousands of people who support Israel. They decided to have workshops on a wide range of issues — including the trade unions. But that workshop had almost no people attending, in part because many of those at the event were not union members, but also because many in the community didn’t get just how important the fight was in the unions.

The resolution adopted by the TUC should be a wake up call to the Jewish community and to all those in Britain who are concerned about growing support for Islamic fundamentalism and the rise of anti-Semitism.

Let’s be clear about just how significant this is: Unions are the main donors to the Labour Party, which is expected to win the elections in May 2015. In other words, we could be only 8 months away from a Labour Government which is going to be strongly influenced by unions which now support an arms embargo and worse.

The defeat suffered by the pro-peace camp at the TUC this week is a devastating blow — but it is reversible.

If resources can be found to bolster the work done by TUFI, TULIP and others — we can at the very least challenge some of the ideas that now go unchallenged at a TUC conference.

I remain convinced that we have the better arguments, and that if we can make ourselves heard, we can win over hearts and minds. Even in the unions.

But is anyone in the Jewish community in Britain, or anyone in Israel, even listening?