Today, as every day, police protection will be at its highest around the Queen and the prime minister and around a politician who in normal circumstances would barely need guarding. Fifteen armed officers, trained in counter-terrorism and emergency medicine, will be on alert solely because a brown-skinned Muslim, caught up in a global wave of hatred, is the mayor of London. The level of threat Sadiq Khan must live with challenges the self-congratulatory claim that “Britain is the least racist country in the world” and many other complacent cliches. British society tells immigrants and their children that all will be well as long as they assimilate. No family could have tried harder than the Khans. Sadiq’s father, Amanullah, and mother, Sehrun, emigrated from Pakistan in 1968, the year of Enoch Powell’s “rivers of blood” speech. When his son became a Labour MP in 2005, that time of racial intimidation and violence was meant to have passed into an unmarked grave. I am not damning with faint praise when I say that if Khan were a white politician, there would be nothing exceptional about him. Since the voters made him London’s mayor in 2016, he has not shown a trace of sectarianism or religious intolerance. He has described Pride marches as a highlight of his year. When Jeremy Corbyn was in charge of Labour, Khan spoke out against anti-Jewish hatred with more political courage than many of his colleagues could muster. As if to prove the point, the first threats he received did not come from neo-Nazis but from Muslim radicals who condemned his support for same-sex marriage. Khan is a modern social democrat. He might be the progressive mayor of any large European or North American city or a leader of or minister in any centre-left government. Yet how many of his contemporaries have experienced the following? The police took a bomb threat in February so seriously Khan was conducting online meetings while dogs sniffed for explosives in the mayoral office, his staff told me. Last year, police put 24-hour surveillance on his family home because of credible threats against him and his wife. Without publicity, the authorities also sectioned a Nazi sympathiser from Surrey, who threatened to “do something” to Khan, which would mean “we will see him in the news”. So great is the hate staff in City Hall’s public liaison unit are offered counselling to help them cope with the volume of racist, Islamophobic, violent and abusive messages they see, and pass on to detectives. A second myth follows the assertion that the assimilated have nothing to fear in the world’s least racist country. Whenever far-right terrorists spoil the national image by murdering Jo Cox or threatening to murder Khan, conventional conservatives jump up to say we cannot call them “terrorists”. They are “mentally ill” loners, in the Lee Harvey Oswald mould, who do not represent darker forces in wider society. You could forgive Khan for replying that he has enough “loners” after him to fill a stadium. As Brenton Tarrant prepared to massacre 51 people in Christchurch mosques, he found the time to urge his supporters to show their commitment to a “white rebirth” by removing the “Pakistani Muslim invader [who] now sits as representative for the people of London”. “Why would a terrorist in New Zealand know about me?” Khan asked. His answer comes from the great reactionary year of 2016 that pushed conservatism rightwards. As he was preparing for the May election in London, Boris Johnson and his Vote Leave team were swinging the Brexit referendum with the lie – and there is no other word for it – that Muslim Turkey with its population of 76m “is joining the EU”. At the same moment, US commentators were dismissing the presidential run of Donald Trump and did not see that he would win in November on an anti-Muslim ticket. Khan experienced the new rightwing politics in the campaign of the Conservative contender, Zac Goldsmith, a member of the upper class, who showed how the mainstream could exploit the lunatic fringe. The Conservatives sought to widen communal divisions between London’s Muslims, Hindus and Sikhs. Khan was a Muslim, they maintained, and if not quite a terrorist then a “Labour lackey who speaks alongside extremists”. I remember thinking at the time that the dog whistles were so loud, you couldn’t hear yourself speak. During the 20th century, anti-Jewish hatred was Janus-faced. On the one hand, it exploited resentment from below by pretending that a Jewish elite controlled the capitalist banks and media, along with (and don’t ask how) the Soviet Communist party. On the other, it exploited resentment from above about immigrants with an alien religion undercutting wages and stealing jobs. Today’s far right plays both sides when it says the global elite is replacing white people by flooding the west with immigrants. Khan lives with danger because he has become the first prominent Muslim politician it can claim is a member of the elite. Trump may be deranged but he is hardly a loner. He was president of the US and may be again. He endorsed Katie Hopkins, who pretends that Khan has allowed no-go areas in London where sharia law rules. You can see the same cry echoed on Twitter to this day. Conservative newspapers know their readership and understand that putting Khan’s name in a headline guarantees angry clicks. No attack on Khan is too trivial to dismiss. They will generate traffic by seizing on criticism of him from figures as obscure as Piers Morgan’s son. Khan said he had kept quiet about the dangers he faced because he did not want to deter people from minorities from going into politics. Then he realised that black footballers did not duck the issue of racism for fear they would put the young off sport. They wanted to fight it and so should he. Silence “normalised extremism”, he told me, and he had had enough of keeping quiet. The mayor of our capital city needs 24/7 protection because of his faith. If you appreciate the consequences of the threat he faces, you must conclude the world’s “least racist country” is not anti-racist enough.