In “Suspect Community: People’s Experience of the Prevention of Terrorism Acts in Britain”, Professor Paddy Hillyard produced what remains the world’s most detailed ethnographic study of the impact of repressive laws and state policies on what we now call “radicalisation”. That was 1993. Hillyard, a former chair of the National Council of Civil Liberties (now Liberty), had interviewed more than 100 people of Irish catholic descent and provided unequivocal evidence that their everyday treatment at the hands of the British state had boosted support for Irish republicanism, acted as a recruiting sergeant for the IRA and fuelled “the Troubles”. Of course it wasn’t the only “radicalising” factor: Bloody Sunday, a shoot-to-kill policy and state collusion with Loyalist paramilitaries also played their part. As of course did the violence, propaganda and popularity of organisations like the IRA.

We could learn a lot from people like Paddy Hillyard and the incremental moves toward truth and reconciliation in the north of Ireland. Instead, this valuable insight is being steadily exorcised from public debate – as are the similar experiences of Muslim communities at the hands of the British state.

Yesterday the identity of “Jihadi John”, the ISIS executioner-in-chief, was revealed to belong to British citizen Mohammed Emwazi. The human rights group CAGE – the only organisation in Britain who offers legal support to Muslims who have been interrogated or harassed by the security services (support which is readily available to most others questioned by the UK authorities) – produced a 3,000 word dossier detailing his treatment between 2009 and 2013. This included, inter alia, the surveillance of his movements, the interception of his telecommunications, the orchestration of his arrest in Tanzania and transfer to the Netherlands where he was interrogated by MI5, attempts to coerce him into becoming an MI5 informer, harassment of his family and fiancé, and the prevention of his resettlement in Kuwait – all in the absence of any formal allegation, charge or prospect of official recourse.

Since this occurred well before Mohammed Emwazi’s departure from the UK and appearance in Syria as “Jihadi John”, one might have thought our media duty bound to ask whether this and other encounters played any part in his decision to go there. Indeed the most revealing exchange, which should surely have been on the lips of any journalist worth their salt, is the following, spoken by MI5 agent “Nick”: “Listen Mohammed: You’ve got the whole world in front of you; you’re 21 years old; you just finished Uni – why don’t you work for us?” When Mohammed declines, he is told: “You’re going to have a lot of trouble... You’re going to be known... you’re going to be followed... life will be harder for you.”

Let us be clear that whatever else may have transpired since this exchange, here is a credible allegation of state-sanctioned blackmail of one of our citizens upon pain of having his life ruined by unaccountable security forces. When things like this happen to Muslims in Arab dictatorships, we talk about “secret police” and “fearsome security apparatuses”. When they happen here, we put our fingers in our ears and demand that Muslims “get over themselves” and condemn acts of terrorism.

And so it was that Kay Burley of Sky News duly began her interview with a CAGE spokesman by asking “What level of harassment by the security services here in the United Kingdom justifies beheadings?” – a plainly preposterous straw man argument that literally no-one was making. Liberal pin-up Jon Snow also glossed over the evidence produced by CAGE, before getting down to the most important business of the day: demanding that their spokespeople condemn terrorism, and seeking to belittle them when they question why this demand is only ever made of Muslims, or worse still, refuse to participate in the ridiculous spectacle.

It was already a nailed-on certainty that the government and the media would turn the “extremist” spotlight onto CAGE and its supporters in a witch hunt that would make McCarthy blush. But having anointed Peter Oborne the Supreme Ruler of Media Integrity for taking on the Telegraph, perhaps they should ask him what he thinks about CAGE’s treatment at the hands of the establishment. Or reflect on CAGE’s founder and director’s own experience at the hands of MI5, or his three-and-a-half years of illegal detention in Guantanamo Bay and Belmarsh prisons. Nope: they’re just “apologists for terrorism”, guilty until proven innocent.

Human rights and social justice groups should be supporting CAGE in its endeavours to uncover the extra-judicial prosecution of the “war on terror” in this country. They won’t because they’re scared of the “public perception”. Much easier to support free expression from behind the comfort of a “Je Suis Charlie” banner. The country should be having a serious conversation about the way “intelligence-led policing” has undermined our national security and human rights by linking the treatment of Mohammed Emwazi to the discredited use of informants and double agents in Northern Ireland, to the links between MI5 and extremist groups, and to an undercover culture that has perverted the pursuit of social and legal justice in this country. It won’t, because we’ll turn a blind eye to anything at the drop of the T-word.

Something fundamental has to change if we’re to have the grown-up conversations that can inform these policies, and that can temper the appeal of extremism and violence in all quarters.