Dave Rich, author of The Left’s Jewish Problem… (2016), now turns his attention to a wider examination of antisemitism. This new book is full of troubling stories, but one of the more disturbing revelations turns up quite late on, when Rich explains how antisemitism is growing among the young in Britain. Unlike other forms of racism, antisemitism rises as you move down the generations. Those under 25 are “the least likely to say they are just as open to having Jewish friends as they are to having friends from other sections of British society”. More than a quarter of young people agree that “Jews have disproportionate control of powerful institutions, and use that power for their own benefit and against the good of the general population”, compared with just 6% of those over 65. This alone tells us why Rich’s book is so important. Such rising hatred demands that we take antisemitism more seriously and that we look at how we got here. Although I am Jewish myself, I am pretty ignorant of much of the relevant history. I was shaken by some of Rich’s stories from 12th-century England, for instance, when the Crusades led to a huge increase in antisemitic violence. Jews were banned from attending the coronation of King Richard I in 1189, and when some attended anyway, they “were set upon by the crowd, who beat around 30 of them to death”. Orders that Jews should wear badges, bans on Jews entering certain occupations, prohibitions on Jews having Christian servants, trumped-up charges, executions, expulsions, massacres – all took place in Britain long before they were part of Nazi horrors. By reminding us of the historical depth to British antisemitism, this book provides a valuable companion piece to David Baddiel’s recent Jews Don’t Count, which was a sharper read, but more narrowly focused on contemporary experience. Rich reminds us that while antisemitism has taken on many different shapes over the years, some of its ugliest aspects – such as the disproportionate power attributed to the Jews in finance and associations with the killing of children – have returned again and again. He shows how disproportionate is the attention given to Jews in Britain, given the tiny numbers who have settled here. I would have relished even more exploration of the relationship between antisemitism and 20th-century British intellectual life. Rich has little to say about how writers such as TS Eliot or HG Wells gave a cloak of respectability to deep-seated prejudices. But I was particularly drawn by unexpected echoes and contrasts with my own family history. Recently, when researching the experience of my grandfather, who was interned in Britain in 1940, I noted the parallel between his experience here and his experience in Germany, where he was held without trial in 1933. Rich’s great-great-uncle was also interned in Britain in 1940 for a year. He notes the parallel here, not with a foreign experience, but with that of his great-grandfather, who was also interned as an enemy alien in Britain during the first world war. So a sense of vulnerability is passed along through generations and across borders. There were some areas where I found Rich a less compelling guide. Readers of The Left’s Jewish Problem… will not be surprised here by his easy identification of much criticism of Israel with antisemitism. It is quite possible for a British Jew to dismiss any connection with Israel – as Baddiel does, for instance. Rich does not take that line. On the contrary, he is heartfelt about the emotional resonance of Israel for all Jews. “It’s a strange experience for a British Jew to visit Israel… a country where you never have to explain to anyone that you are Jewish… The beauty of the land itself, its mountains and deserts, is infused with a history that even the most secular, atheist Jews find hard to resist.” I felt similarly welcomed the first time I went to Israel, an undoubtedly beautiful land that had given members of my own family sanctuary from persecution. But can Jews outside Israel continue to see it so straightforwardly as a place of welcome? Rich would like to believe so. “I tend to keep my views about Israel’s politics to myself,” he says, “mainly because it shouldn’t matter what I think.” Yet he also, for instance, describes the evictions of Palestinians in the Sheikh Jarrah area of East Jerusalem as “a dispute over a property contract in a suburb of Jerusalem… My point is not to try to sort out who is right and wrong – I’ll leave that to the Israeli courts.” By dismissing these fraught evictions – described by some as a possible war crime – as a property dispute and giving all moral authority to the Israeli state, Rich seems to have already sorted out who he thinks is right. This is not, in fact, an apolitical stance. But Rich’s most precious contribution to the current debate is undoubtedly the line that he draws from historical antisemitism to the crazy conspiracy theories of today. These theories, which put Jewish bankers at the heart of an oppressive global elite, are not only threatening Jews – they are threatening everyone’s hope of making progress towards a more sustainable and equal world. A quick search on social media after reading this book told me, for instance, that Greta Thunberg is descended from the Rothschilds and that billionaire financier and philanthropist George Soros is behind the plan to confine everyone to 15-minute cities. Lies, of course, but lies with legs on social media. As Rich points out, nobody really knows exactly how to deal with these conspiracies and end them for good, but we have to keep exposing them. They grow in the darkness, and however grim the work, they need to be brought into the light. Natasha Walter is the founder and former director of Women for Refugee Women and author of The New Feminism and Living Dolls: The Return of Sexism Everyday Hate: How Antisemitism Is Built Into Our World – and How You Can Change It by Dave Rich is published by Biteback (£20). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply