Shanghai Grand: Forbidden Love and International Intrigue on the Eve of the Second World War Taras Grescoe Macmillan , pp. 401 , £

If there's one country that knows how Britain feels in the wake of last week's suicide bombing in Manchester, it's France. Similar horror has been visited on the French several times in the past five years with nearly 250 slaughtered at the hands of Islamic extremists, so the French are all too familiar with the grief, the rage and the shock still being felt across the Channel.

But not Britain's incomprehension. At first, maybe, when Mohammed Merah shot dead three Jewish schoolchildren in a Toulouse playground five years ago, but since the Charlie Hebdo cartoonists were slaughtered in January 2015 the French have understood what is going on.

The Islamists are waging an ideological war on the West, one that has little to do with foreign policy, colonial legacies or social deprivation, or any other excuse routinely trotted out. They kill because of an ideology that seeks no compromise in its quest for a caliphate in Europe.

That the French now realise this is in no small part because of a political scientist called Gilles Kepel, the most incisive and certainly the most courageous (his work has earned him a place on an Isis death list) of all French writers when it comes to Islamism. Such is Kepel's standing that he was referenced by Emmanuel Macron during last month's presidential debate with Marine Le Pen. Telling the leader of the National Front that her election could unleash a civil war, Macron said that that very morning Kepel had warned that the Islamists' 'greatest wish is to have Marine Le Pen come to power in France'.

Kepel feels Britain's pain but he also fears for them because of the way they have dealt with Islam. This dates back to the 1990s when the French intelligence services rechristened the capital 'Londonistan' on account of the city's enthusiasm for providing shelter to the waifs and strays of the extremist Islamic world. In March this year Gilles Kepel was interviewed in Le Figaro and told the newspaper that the Islamist attack in Westminster 'sounded the death knell for Britain's multicultural dream'.

Kepel is a defender of the French secularism that has been enshrined in law since 1905. It's the opposite approach to British multiculturalism and, in the eyes of many UK commentators, far inferior. The Guardian, in particular, is a fierce critic of laïcité. In January 2015 Giles Fraser, writing in the aftermath of the Charlie Hebdo massacre, described the French attitude to its Muslim population as 'bullying and goading' and advised their government to start 'rethinking their precious laïcité'.

In 2016, not long after an Islamist had driven his 19-tonne lorry over 86 people in Nice, Iman Amrani declared in the Guardian that 'laïcité should in theory promote social harmony between different groups in a multicultural, multi-faith society; but in practice it’s being invoked as the reason for policing Muslims’ day-to-day lives'.

Laïcite isn't perfect, and it clearly hasn't prevented Islamist attacks - that's the job of the intelligence services who, in the last 11 months, have dismantled numerous terrorist cells - but what laïcité does, in the country with Europe's largest Muslim population, is allow one to follow one's faith but not in an ostentatious or aggressive manner. It also stops provocateurs like those in Cannes, who on Friday tried to stage a celebration of the burkini but had their mischief quickly curtailed by the police in an encouraging sign that the new government will tolerate no rabble-rousing.

Britain, on the other hand, has bent over backwards to accommodate Islam with its unshakeable belief in multiculturalism, and look how it's been repaid - bombed by the son of a Libyan exile who was given refuge 25 years ago. Boualem Sansal, the Algerian writer, who in 2015 was awarded the Académie Française's literary prize for his novel '2084: the end of the world', is concerned by the naivety of Western countries that still believe multiculturalism is the way forward. 'For Islamists, it's an insult to Islam,' he said in an interview in today's Le Figaro. 'Nothing can be equal [to Islam]. Nothing can pollute its environment.' For proof, said Sansal, simply visit those inner-city areas in Europe where the Islamists hold sway. What do you see? 'Not one plucky Christian, not a trace of a Jew, nor a homosexual, no artists, no free-thinkers, not a woman wearing trousers'.

In recent years, the weakness of some local councils in France in defending laïcité has allowed the Islamists to impose their beliefs in a number of districts. It's important that Emmanuel Macron roots out the appeasers because, as Keppel recently explained in an interview in English, laïcité is in place to protect Muslims from a 'fundamental Islam that considers that only Salafists are true Muslims and the others, the bad Muslims, are apostates'.

What laïcité doesn't do, and the reason why it's scorned by so many on the British left, is 'celebrate diversity'. This has been the British dogma for a quarter of a century and it's clearly not worked, as was laid bare last year by Trevor Phillips, when the former head of the Equality and Human Rights Commission warned that 'squeamishness about addressing diversity and its discontents risks allowing our country to sleepwalk to a catastrophe that will set community against community'.

Kepel shares this assessment, worried that Britain has yet to grasp the incompatibility of its values with those of the Islamists. 'The United Kingdom has driven a policy of prevention but also of devolving entire districts to the Islamists, notably tolerating Islamic tribunals, in order to buy social peace,' he explained. 'The acceptance of a form of separatism, an 'apartheid', as is the case in Birmingham with his Sharia judges passing sentence, poses a very big problem for their values.'

Laïcité, in contrast, unashamedly promotes French values above all others, be they Catholic, Muslim or Jewish. All religions are respected - but the Republic comes first. In short, laïcité is the glue that holds the country together and that's why the Islamists have failed to fracture France despite five years of sickening violence.