LONDON — Two weeks ago, the chairman of the Yesh Atid party faced the cameras at the start of a faction meeting and melodramatically brandished color photographs of anti-Israel posters that BDS activists had hung in London’s subway system. Yair Lapid assailed the government and claimed that since it wasn’t doing anything, he had to intervene: He “contacted his friend,” London Mayor Boris Johnson, “explained” the gravity of the situation to him and urged him to order the posters taken down.

But, as in many other cases, the pyrotechnics and the bombastic patriotic speeches concealed an insipid reality, a generous helping of spin and a lot of petty politics. Sources well-acquainted with the incident, who asked to remain anonymous, said that despite the impression Lapid tried to create, there was no telephone call between him and Johnson.

Lapid, these sources said, did nothing more than send Johnson a message on WhatsApp. The answer he received — and it’s not even clear whether it came from Johnson or one of his aides — was laconic. “It was something along the lines of ‘We’ll look into it,’” one source said. Lapid, who is rightly critical of the fact that the current government has no full-time foreign minister, has apparently created a new kind of diplomacy in which the problem is solved the moment two blue check-marks appear on your smartphone screen.

But the response by Prime Minister Benjamin Netanyahu and his staff was no less hysterical. In the face of Lapid’s attack, Netanyahu quickly made a panicked phone call to Foreign Ministry director general Dore Gold, who happened at that moment to be in the midst of an Israeli-British strategic dialogue session at the British Foreign Office in Whitehall.

British diplomats described how, before the astonished gaze of the Foreign Office’s permanent undersecretary, Simon McDonald, Gold was pulled out of the conference room to receive instructions from Netanyahu. After a few minutes, he returned to his seat and voiced a protest against the posters, which had already been removed two hours earlier by employees of the City of London’s public transportation department — who hadn’t waited for any orders from Lapid or Netanyahu.

A few hours after this incident, as part of a public diplomacy offensive (whose target wasn’t BDS, but Lapid), I got a phone call from Gold. As he was describing, in his usual courteous, pleasant manner, the excellent atmosphere in his talks with the British, I could hear some of his aides in the background. “Tell him about BDS, tell about him about BDS,” they urged him. So he did.

The true picture of the BDS phenomenon in Britain is far more complex than the panic that has gripped both coalition and opposition politicians over the last few months. One could describe it as a mixture of “oy vey” and “let us rejoice.” Or as an old Arab expression put it, “Honey one day, onion the next.”

On one hand, this is no made-up problem. There are more than a few people and organizations in Britain, some of them tainted with anti-Semitism, that are fundamentally hostile to Israel in a way that goes far beyond legitimate criticism of its almost 50-year-old occupation of the territories, its building in the settlements in violation of international law, and its violations of Palestinians’ human rights. They can be found on the kingdom’s biggest campuses, in parts of the British media and in some of the parties in parliament.

Some BDS supporters are also affiliated with Labour Party leader Jeremy Corbyn’s inner circle. Corbyn’s son heads a pro-Palestinian student group at the university where he studies, and he even played an active part in the recent “Israel Apartheid Week” events on British campuses.

This anti-Israel atmosphere, which rejects the very existence of a nation-state for the Jewish people, has also penetrated public opinion, especially among young liberals. Many of them have no knowledge of the details and complexities of the Israeli-Palestinian conflict, and they see it as a zero-sum game in which it’s impossible to be both pro-Israel and pro-Palestinian.

On the other hand, Israel’s standing isn’t in total free-fall. In the last public opinion poll that asked respondents which side in the conflict they identify more with, the result was a tie. Twenty percent of British respondents sided with the Palestinians and the same percentage sided with Israel; the other 60 percent were undecided.

Lapid’s claim that nothing has been done to combat BDS looks even more ridiculous when you see the map of Britain hanging on the wall in the office of Yiftah Curiel, spokesman of the Israeli embassy in London. Like the war room of a brigade on the Lebanese border, the map shows the front — the main campuses, the deployment of pro-Israel activists and the location of the “enemy forces.”

Curiel, a diplomat and son of a diplomat, coordinates the anti-BDS activity in Britain. Under the leadership of Eitan Na'eh, the acting ambassador, Curiel and other embassy employees, working together with British friends, are fighting. They are doing so quietly, without histrionics. Without making light of the threat, but also without inflating it. Sometimes they suffer losses, but often they win.

Take, for instance, the instructions forbidding boycotts of Israel that the British government issued to public-sector agencies and municipalities. Or the creation over the last four years of a network of more than 40 pro-Israel organizations throughout Britain. Or the changing trend in Scotland, which used to be the most anti-Israel region in the kingdom. Or the way young members of both the Labour and Conservative parties are flocking to the Israeli embassy to get seats on the plane for an educational tour of Israel sponsored by the Foreign Ministry.

One of the key people responsible for building the pro-Israel network in Britain was diplomat Ishmael Khaldi, who returned to Israel a few months ago after completing his posting in the United Kingdom. How shameful it is that while a Bedouin Israeli diplomat was running around Britain fighting boycotts and BDS activists, he had to watch in frustration as the government in whose name he spoke refused to lift a finger to build the basic infrastructure that would enable normal life in his home village of Khawaled.

But the very complexity of the BDS picture in Britain, coupled with Israel’s need for help from every possible friendly party, makes it hard to understand the way the Israeli embassy in London treats a relatively small Jewish Zionist organization that was founded in Britain a few years ago. Like its American cousin J Street, the liberal-leftist group Yachad describes itself as “pro-Israel, pro-peace” and works to promote a two-state solution.

This week, Yachad and the British branch of the New Israel Fund held a conference in London on the topic of Israeli security. Full disclosure: I was invited to the conference as a speaker and moderator, and Yachad financed my flight and my stay in the city. The views of the conference speakers and the 250 participants spanned the narrow gamut from the Israeli Labor Party to the right flank of Meretz. I sometimes felt like the most radical person present.

A few weeks before the conference, Yachad director Hannah Weisfeld sent an official invitation to the embassy in London asking an embassy representative to address the conference and present the government’s position. The embassy turned down the invitation on the pretext of a scheduling problem.

The real reason for the embassy’s decision not to send someone to speak at the conference was Yachad’s criticism of construction in the settlements and its statement of support for a decision requiring settlement products to be labeled throughout the European Union, something the British government had pushed for. But the straw that broke the camel’s back was the letter of support the organization sent Prime Minister David Cameron after a speech in parliament in which he voiced shock over the expansion of Jewish settlement in East Jerusalem.

We’ve long known that the Israeli government doesn’t look kindly on Israeli citizens who criticize the occupation to the British government. It now turns out that British Jews are also forbidden to express support for their own government’s policies.

Israeli diplomats say they aren’t boycotting Yachad; they have an ongoing dialogue with its leaders and even get help from the organization in the battle against BDS. Even if Jerusalem won’t admit it, the liberal leftists of Yachad, who spare no criticism of Israel’s policies in the territories, are its most effective agents in Britain. BDS activists have trouble dealing with their message.

It was enough to see how Weisfeld, the group’s director, made mincemeat of BDS supporters at a recent event at the University of Southampton. The Israeli embassy’s enthusiasm over what happened at that event makes its decision not to officially attend Yachad’s conference even more foolish and surprising.

Yachad in Britain and J Street in America could be Israel’s “Iron Dome” against BDS. If the Israeli government boycotts them, pushes them away and doesn’t learn how to listen to and digest their criticism of its policies, it will lose important allies in the battle for Israel’s security and its future.