It is the small insidious things that you start to notice. Sipping coffee in the ‘green room’ at a TV studio the comedian, who is to appear before me, cracks what he thinks is a funny joke: “Philip Green, fancy yachts and Ken Livingstone, it all makes sense doesn’t it.”

The friendly letters I have received from Daily Mail readers praising our passionate coverage of BHS and then reminding me, as if I didn’t know, in bold underlined letters he is a ‘JEW’ after all. And the Tory MP Richard Fuller calling for Parliamentary justice for the BHS pensioners after infelicitously talking about the owners taking their ’20 pieces of silver’.

Regarding Sadiq Khan’s campaign for mayor of London: it is an enormous achievement for the son of a bus driver from Tooting and human rights lawyer to be elected as mayor of the world’s financial and global city. His opponent Zac Goldsmith, my MP in Richmond Park and proud of his Jewish heritage, is accused of ‘dog-whistle’ politics for daring to question the affiliations of some of the radical preachers and Hamas supporters with whom Khan has shared platforms.

We know from Ken Livingstone’s revealed views that the radical Islamic company he has kept was no accident. We also know from the way in which the anti-Zionism of the left has flourished in the Labour Party of Jeremy Corbyn and John McDonnell, when it was largely sidelined and controlled under the previous leadership, that something dramatically changed. Even after weeks of revelations of hostility to Jews and Israel in the national media, it is not considered safe in Britain to voice concerns.

One narrative heard from politicians of the left is that anti-Semitism has been whipped up by the right-wing press as a means of harming Khan and others, so it can be safely ignored. When my colleague Isabel Oakeshott questioned the Labour leader’s sympathy for Hamas and Hezbollah on the BBC1’s Question Time, the booing rang out across the hall in Manchester.

For a long time both as journalist and (in the last triennial) as an elected officer of the Board of Deputies of British Jews, I bought into the idea that anti-Zionism and anti-Semitism could be exaggerated and that we were uniquely lucky in Britain that we are such a tolerant society.

We applaud the election of the first Muslim mayor of a major European city. We are accepting of the idea that Britain’s biggest Islamic charity, Islamic Relief, is taking advertising space on buses with the strapline ‘Subhan Allah’ – glory be to God in Arabic – as part of a Ramadan campaign to raise money for use in war-torn countries such as Syria and Iraq. Would Britain’s secular society be happy if the Church of England spent its money on big bus posters proclaiming the name of Jesus during Lent?

The return of anti-Semitism to Europe is explored in detail in an article by Brendan Simms and Charlie Laderman in the New Statesman under the heading: The longest hatred: Anti-Semitism is resurgent in Europe. Can this ancient poison ever be eradicated? Anyone who has closely monitored the rise of nasty far-right and left parties in Europe, amid the spread of economic desperation, could not but be fearful of what is happening. At home, anti-Zionist and anti-Jewish sentiments have become mainstream. We know from the Brussels attacks how ISIS gained a hold in Belgium. What we also need to understand is that the Brussels Jewish community has long felt under siege from anti-Zionist elements.

The good news, such as it is, in Europe is that anti-Semitism tends to be where you would expect among radical Islamists and in fringe parties such as Jobbick in Hungary, Greece’s Golden Dawn and deep within the National Front in France. The mainstream parties and politicians, such as French President François Hollande, have no truck with such sentiments.

The disturbing thing in Britain is that anti-Semitism is polluting Labour, the nation’s main opposition party. That makes it so much harder for mainstream parties to build a common front against extremism.

One wants to believe that Labour is still the party of Harold Wilson, Tony Blair, Gordon Brown and Ed Miliband: all great sympathisers to things Jewish and to Israel. But it clearly is not and Britain is in danger of allowing the oldest hatred to more broadly affect our culture.