David Cameron has neither turned gaunt, haunted by the failure of his EU referendum gambit, nor plump, relaxed and fleshed out by release from office.  Present and correct in blue to address the evening’s event – blue suit, blue checked shirt, blue tie – he looks unchanged from the man who left Downing Street less than two years ago.  It is as though he has time-travelled from his premiership and in some strange sense still occupies it.  As so often, he presents impeccably: his hands slice the air for emphasis, or spread wide to appeal for support; he leans back to reflect, forward to force a point; swivels from the waist to draw attention.  He holds the room.  I surprise myself by wondering if Parliament has really seen the last of him.

But while it may have done, politics, more broadly, has not.  Cameron is here to speak about one of his interests and make an appeal.  As a member of his front bench team before the 2010 election, I saw at first hand how he shaped a policy response to Islamist extremism – a challenge that absorbed him.  It still does.  He is here at a dinner at the invitation of Policy Exchange to lead a discussion on what should be done next: to acknowledge successes, admit failures – and offer advice, as you will see.  The think-tank has led the way on influencing Government policy on extremism.  And if you want large-scale polling of British Muslims, look no further.  At any rate, I can’t think of another with the reach to bring together 50 or so experts, wonks, and diplomats in America’s capital for an event like this.

Now for that advice.  Cameron wants to take issue (though he is too courtly to do so directly) with the country’s two most recent presidents – or, as he puts it, with the Left and the Right.  The latter, he says, sometimes holds Islam, the religion, responsible for terror and extremism carried out by Muslims.  Meanwhile, the Left can refuse to acknowledge that Islam is connected to both at all.  Or, as he puts it, “parts of the Right say that it has everything to do with Islam; parts of the Left that it has nothing to do with Islam.  Both are wrong.”  The spectres of Donald Trump, with his tweets denouncing Islamic terrorism, and of Barack Obama, who studiously avoided mention of the religion, hover briefly in the room.

Cameron’s take is familiar.  The root of the problem is Islamism, the ideology, not Islam, the religion – though the two are obviously related, the first being a distortion of the second.  Foreign policy, poverty, discrimination, broken families: all these can help to inflame and contribute to extremism and violence (though a significant proportion of Islamist terrorists are middle-class or converts or both), but they are not the driving force behind them.  Islamist ideology – even when pared down to a hatred of non-Muslims – is key: the trigger, if you like, that sets the bomb off.  It is suspicious of liberal democracy at best, violently opposed to it at worst.  Muslims themselves are in the front line of the struggle: Cameron refers to “a civil war within Islam worldwide”.

So far, so obvious.  His government deported Abu Hamza and Abu Qatada; it stopped some hate preachers getting in to Britain; it refused to share platforms with Islamist-leaning groups, and cut off their patronage and funding.  It tried to tame the teeming presence of hate online.  (Cameron is still preocuppied with this as an unresolved problem.)  He commissioned a report on the Muslim Brotherhood to try to get the bottom of what it thinks and wants.  The flavour can be sampled in this ConservativeHome piece by the review’s author, Sir John Jenkins: “people sometimes say that we need to identify moderates inside such organisations and detach them by engagement from their more extreme colleagues…I can’t think of a single example where this has actually happened.”

But identifying the problem clearly, and seeing the policy through in Whitehall, has proved grindingly hard.  Theresa May wanted an Extremism Bill – with Extremism Disruption Orders and Extremism Banning Orders targeting Islamist and neo-nazi groups.  But no workable definition of extremism has been found to date and the project collapsed.  Civil servants and the Conservative Party’s own policy apparatus have seemed incapable of distinguishing between religious conservatism and political ideology – with at least one Tory MP writing to constituents that Extremism Disruption Orders would in some circumstances “apply to a situation where a teacher was specifically teaching that gay marriage is wrong”.  These tensions are also felt in the Casey Review and Sajid Javid’s integration strategy.

Three thoughts.  First, government is not well suited to assist the creation of mass movements of mainstream Muslims.  Most politicians are not themselves Muslims, and those who are Muslims are none the less not theologians.  Second, it is better placed to do what Cameron’s government strove to do: “choose our friends wisely”, as a Policy Exchange pamphlet put it, and give or withhold patronage, shared platforms and publicity.  It surely cannot be beyond the wit of Whitehall to draw up a definition of extremism that would identify opposition to liberal democracy, and the trumping of common citizenship by religious identity in the public square, as distinguishing factors. Muslim Brotherhood and Jammat Islami-linked organisations must continue to be held at arms’ length.

Finally, policy cannot be all stick and no carrot.  To what degree government should engage with religious identity at all – be it Muslim or Christian or non-believing or anything else – will inevitably be debated back and forth.  But it is incontestable that, for all Britain’s standing as a plural country, anti-Muslim hatred and violence is real.  (See Javid on the matter in today’s news.)  Tell MAMA, which comes as close to doing for Muslims what the Community Security Trust does for the Jewish community as anyone, claimed last year that a mosque is targeted once a week.  We back an inquiry into anti-Muslim hatred.

Mention of violence returns one to the biggest threat to public security – the Islamist one that murdered 23 people in Manchester last year and eight near London Bridge.  In the wake of the use of a chemical weapon in Britain, and the escalating war of words and measures between Britain and Russia, it may seem strange to write about the Islamist threat, both violent and non-violent.  None the less, “it hasn’t gone away, you know”, to adapt what Gerry Adams once said of the IRA.  We need reminding of the scale of the challenge – whether by a former Prime Minister or almost anyone else.