It was, declared Lord Kestenbaum, opening the We Believe in Israel conference on Sunday, the largest single gathering in Britain on behalf of Israel.

It encompassed all shades of political and religious opinion, all ages - with a healthy 20 per cent of student age - and included both Jewish and non-Jewish supporters of Israel, particularly from churches, trade unions, and political parties.

"We as a community will, at times, disagree," Lord Kestenbaum noted wryly. "But there is no disagreement on our core principle, of support for Israel as a democratic Jewish state. And that is the legitimacy under assault. What may have once been taken for granted, cannot any longer be guaranteed." But with this conference, he said: "We will not be seen as the generation who did not do enough."

And with those few remarks, an extraordinary day unfolded, both familiar and unfamiliar in its agenda. It was an event with a familiar ring to anyone who has ever taken part in a Jewish student conference, a youth movement, or Limmud, in the moving from workshop to workshop, corridor to corridor, with multiple stops for both physical and mental refuelling.

But the unfamiliarity of the We Believe in Israel conference was that the thrust of the many speeches and addresses was not simply the words themselves, but a rallying call to British Jews and their friends and allies. And the call was: get organised. Establish a network. Begin the fight-back for Israel.

The event was topped and tailed with two standing-room only plenary sessions, beginning in the morning with British Defence Secretary Dr Liam Fox, Israel's ambassador to the UK, Ron Prosor, and his counterpart in Tel Aviv, Britain's ambassador, Matthew Gould.

Not everyone in the audience appreciated Dr Fox's remarks when he spoke of the British government's response to settlement activities, which, he said, "we believe are illegal and an obstacle to peace". But the majority of his speech drew warm applause, particularly when he spoke about standing firm on Iran. "Iran's nuclear capability will not be tolerated by the international community," Dr Fox declared. "We will not look away on this and we will not back down." And in the week of Israel's 63rd anniversary, the Defence Secretary made clear that "if the candle of Israel's democracy diminishes, then so does hope for the entire region". A future Palestinian administration, he said, would be judged by its actions and its readiness for peace.

"Britain is and will remain a friend to Israel," Dr Fox said. "We are proud to believe in Israel."

Israel's outgoing ambassador to the UK, Ron Prosor, was a crowd favourite after making the case for Israel in the most difficult circumstances over the past four years. On his way to New York where he will represent Israel at the United Nations, Mr Prosor spoke with regret of the diminishing public image of his country, and the change in climate which meant that "there is not a campus in this country where an Israeli can speak without some form of harassment". The delegitimisers, he said, were "targeting our soft underbelly by seeking to cast us out of the family of nations".

But Mr Prosor declared: "Our adversaries are crossing the line but no-one is stopping them. It is up to us to speak out, far more robustly and with a crystal clear response. We need more pride in Israel."

One of those most proud, paradoxically, is Britain's ambassador to Israel. Matthew Gould is Britain's first Jewish ambassador to Israel and in the seven months since his arrival in Tel Aviv he has done his utmost to bring the two countries together.

He spoke with emotional warmth of his grandfather, who had been given refuge by Britain, and who, he liked to think, would have felt "enormous pride to see his great-granddaughter born in Israel, six weeks ago. She is named Rachel after my great-grandmother from Lodz".

In three brief snapshots, Mr Gould summed up his impressions of Israel: technology, education, and the tragedy of terrorism. He had seen groundbreaking developments in non-invasive surgery, an Israeli development "which could revolutionise medicine and transform lives across the world". He had visited the "compelling Zionist ideal" at Kibbutz Eshbal in the Galilee, an educational project providing help and support for troubled teens, supported by the UJIA. And, finally, he had held the hand of the grandmother of Daniel Viflic, who held joint British and Israeli nationality, at the funeral of the 16-year-old, killed in April when a Hamas rocket hit his school bus.

"This is not about handshakes on the White House lawn," Mr Gould said. "It is about no more 16-year-old boys, on either side, being buried by their parents. No more funerals like Daniel's funeral."

The rapturous standing ovations for the three men who opened the conference were echoed at the end of the day in response to speeches by Colonel Richard Kemp, Israeli Education Minister Gideon Sa'ar, and the diminutive chairman of the Jewish Agency, former Prisoner of Zion Natan Sharansky. It was Mr Sharansky who best caught the spirit of the day-long event when he recalled the long-running, and ultimately successful, Soviet Jewry campaign which helped free him and many other Prisoners of Conscience.

During his nine years in prison in the Soviet Union, he recalled, the KGB frequently tormented him by telling him that no-one cared about him and his plight. "The only people taking any notice are students and housewives," the KGB agents said. That was certainly true, Mr Sharansky said. "But they were Jewish students and Jewish housewives, who decided that they could not be silent. And they started contacting refuseniks. And then the Jewish organisations started sending, first dozens, and then hundreds of people to the Soviet Union so that we could deliver our message. We didn't have Facebook or CNN. But it was done by thousands of Jews who insisted they could not be silent and had to let the world know."

It was a lesson, said Mr Sharansky, on how Jews working in coalition could deliver a powerful message. "And today we do have Facebook, and the internet, and we do have powerful media." Forty communal organisations, together with the JC as media sponsor, joined together to make the advocacy conference work.

Mick Davis, chairman of the UJIA and of the Jewish Leadership Council, made an impassioned plea for local activism to be the natural outcome of the event. Supporting Israel as a Jewish democratic state was within everyone's grasp, he said. Getting the message across was the task ahead.

Overall attendance

Most popular sessions: through the day (repeated sessions)

on polling

delegitimisation

art of persuasion

difficult arguments.

at a single session of revolution/uprising.

speakers

lunch packs prepared (but they still ran short of food).

Around

per cent of participants were of student age.

In the crowd:

The session, Do They Really Hate Us? heard about new polling from Rick Nye of Populus, in which more than 5,000 people were asked for their views on Israel. The polling also looked at the relative success of different arguments in making Israel's case.

On the big picture, two-thirds of the public think that ordinary Israelis reject the idea of a Palestinian state; only a small majority even among the most pro-Israel part of the population believe that ordinary Israelis accept the idea.

Two-thirds think Israel would rather keep its settlements than have real peace and security. Even the most pro-Israel segment splits 50:50 on this.

Two-thirds think Israel has never offered to give up land for peace in the past - an especially important finding given that more people see the conflict as territorial rather than religious.

The poll showed that some arguments were very persuasive, while others could have a negative effect.

Half of the public said they were more sympathetic to Israel when told that Israel had offered to give up large areas of its land for peace in the past - by far the most persuasive argument.

Even two in five of the most anti-Israel part of the population said this made them more sympathetic. Freedom of worship made two in five more sympathetic overall, and one in three of those most hostile to Israel.

But asserting that Israel is part of the war on terror alienates at least as many as it attracts unless people are generally more favourable towards Israel to begin with. A sizeable minority believe it to be untrue.