Dewsbury, New Southgate, Small Heath, Stockwell and, on Friday, the most telling pictures of all - the two suspected bombers appearing on the terrace of their Peabody Estate flat in west London. It's been a catalogue of familiar terrace and semi-detached houses intermingled with housing estate flats that seem indistinguishable, whether in London, Birmingham or Yorkshire; a snapshot of Britain's not-so-glorious underbelly but a vivid visual reminder that the men who have murdered us, or tried to, were either born and bred in Britain or made their homes here.The ties that bind and the minimal shared assumptions that might fend off savage hatred have not operated; these are men so disaffected with Britishness that they have sought identity and meaning in the doctrines of jihad, martyrdom and the casting of their fellow citizens as valueless infidel who can be murdered without conscience. Nor are they alone. They represent a vital sub-culture that may be a minority but is growing and casts long shadows among the generality of British Muslims. In New Southgate we watched a young British Muslim outside the ninth floor flat of a suspected bomber express his sympathy with the ideas of martyrdom.It's a disconnect that is more general; when the reportedly rational leader of Birmingham's Central Mosque says that he does not trust the word of the police and government about the Islamic identity of the bombers, it is symbolic of what has happened. Britain, the writ of Britishness and what seems obvious to the rest of us leaves a critical mass of British Muslims cold; they refuse to believe what is palpably true. Whatever mix of responses you think are needed to lift the threat of the bombs - changing British foreign policy or sharper intelligence - part of the story will have to be persuading young British Muslims that Britishness is an idea worth a minimal degree of loyalty that inhibits mass murder. The question is whether it's up to such a task. Do the British even have a shared conception of what our identity is?This is a debate where the markers are already being put down by the ascendant right, and the undertones are ugly. Britain is in this vulnerable position, runs the argument, because it has been too liberal across the board - from allowing asylum seekers from Somalia and Eritrea to carelessness about non-English speaking imams spreading jihad in British mosques. On that bridgehead of shared concern, it's not hard to take the conservative argument further; Britain is too polyglot, access to its generous welfare state is too easy and there's been too much concern for tolerance, observance of human rights and concern for the underdog. And this speaks to a so far unspoken but just below the surface sentiment; Enoch Powell's warning that the streets would one day run with blood has been proved right. Britishness must be recast around conservative values and the same mistake not made again.This is all too combustible tinder, but one of the paradoxical saving graces of Britishness is that it is too vague an idea to be deployed in such a way. Whether Norman Davies documenting how Britain has been constructed from successive waves of immigration in The Isles, or historian Linda Colley describing how Britain was essentially an eighteenth century political artefact as the result of the union of England, Wales and Scotland in Britons, both unite to show how the idea of Britain is not a faith like the idea of, say, France, or America - or nationalistic like the idea of China or Russia.It's a political jurisdiction that has common practical mores while allowing our emotional identity to be rooted in one of the tribes from which the country has been constituted over time - English, Welsh, Scottish, Jews - and for immigrants, India, Nigeria or Barbados.Even if we want to make Britishness more assertive and conservative or even to harden it into a citizenship test, it won't wash. One of the reasons Euroscepticism is so difficult to counter in Britain is that beyond the shared political symbols of British sovereignty there's not much more that's common to the story - which is why sovereignty counts so much.You can tell a story of Britain that is about Gray's Elegy, the James I Bible, D-Day and Elgar; or you can tell a story of Britain about the Levellers, Methodists, Monty Python and Willam Wallace. The idea encompasses multiple traditions, stories, tribes and eccentricities; belonging means little more than speaking the language, recognising the complexities and achievements while acknowledging the minimal rules that flow from the political arrangements. The tolerance is in the DNA.The problem for Pakistanis, Eritreans and Somalians is that the tribe to which they emotionally belong within the British accommodation does not command anything like the same loyalty as being British English, British Indian or even British Jamaican. Being British and English, or British and Indian works; being British Pakistani or Eritrean does not. They come from broken-backed countries that have no proud history, culture or identity - Pakistan, for example, is only 58 years old: the identity that makes more proud sense is Islam. And in one jump young British Muslim Somalians, Eritreans and Pakistanis are suddenly in the vortex of a culture and religion profoundly wounded by globalisation, Western foreign policy and its own failure to match the rise of Christendom - with all its capacity to transmute a doctrine of peace into a doctrine of sexism, murder and anti-semitism.Nobody can be sure how it will end, but trying to concoct a new urgent conservative British faith as part of a concerted effort to persuade young British Muslims of the value of their adopted country will not be part of any solution - however much some may wish it. Britishness does not admit of such manipulation, which is why millions of British are so loyal to the idea even while not being overtly loud about it. What will happen, I suspect, is that the British will carry on with their understated Britishness while keeping the invitation open - even to jihadist-inclined British Muslims whose parents came from Eritrea, Somalia and Pakistan - to join the club because in the end, however sorely tempted we are, the invitation can't be withdrawn.It's not how British identity is emotionally constituted. And enough British Muslims will find the same value in the co-existing identities to resist the temptations of jihad, and to marginalize the wannabe murderers in their midst. Indeed, it may be in Britain that radical Islam meets its match; and where Islam starts to convert to modernity. Long odds, maybe - but not impossible.