"These are sad days man, sad days; it's just … surreal." Six months ago Lethal Bizzle and I had talked about how grime had exploded into the political sphere, soundtracking the winter's youth and student protests in London, but now the 28-year old rapper is much less upbeat, surveying the wreckage in the city he loves. "Watching it on TV's been even worse – it doesn't even feel like it's London, or Britain – it doesn't seem real. You know when you see Iraq, foreign wars on TV…" he tails off, before reflecting on the Walthamstow in which he grew up. "I care because I'm from these places, and I know what happens. I've been through stuff I wouldn't want my kids, my friends, my fans, anyone to go through. It makes you feel lost, like you're in a corner."

Two decades ago Chuck D famously described rap music as "the black CNN" – a means of describing the kind of daily lives which the real news network would never care to investigate; by this token, grime and UK rap is the BBC News 24 of the British urban working-class – not necessarily black, not necessarily young, but mostly so. As the glaziers and magistrates go to work after four nights of riots across London and the UK, the search for understanding and the finger of blame are simultaneously pointing towards the MCs and rappers who Bizzle told me in January were "the real prime ministers of this country".

Grime describes the world politicians of all parties have ignored – its misery (eg Dizzee Rascal's Sitting Here), its volatile energy (Lethal Bizzle's Pow), its gleeful rowdiness (Mr Wong's Orchestra Boroughs), its self-knowledge (Wiley's Oxford Street), its local pride (Southside Allstars' Southside Run Tings), down even to minor specifics. When some Londoners expressed their surprise and admiration at the quasi-vigilantism of "Turksec" in Dalston and Hackney, the north London Turkish community who fought off looters with a mixture of togetherness and baseball bats, most grime fans' first thought was Wiley's offhand lyric: "I had this Turkish bredrin from school, all his family were gangsters."

So what are the grime MCs saying now? In the era of frenetic 24-hour news, live-blogging and Twitter, the response has been quick, honest and instinctive. I was initially directed to Tottenham on Saturday evening after seeing a tweet from Wretch 32 that enigmatically read: "Wish I was there. If you know u know." It didn't take long to work out where, and what, he was referring to. His fellow MCs Skepta and Chipmunk, all from Tottenham, had already posted RIP messages in memory of Mark Duggan. Another leading Tottenham MC, Scorcher, tweeted that Saturday night: "25 years ago police killed my grandma in her house in Tottenham and the whole ends rioted, 25 years on and they're still keepin up fuckry"; it was the death of his grandmother Cynthia Jarrett, who died of a stroke following a police raid on her home, which sparked the Broadwater Farm riots of 1985 (Scorcher was born the following year). In a tweet, Scorcher commended well-known community activist Stafford Scott for "talking up the tings like a bludclart general" on the news.

Some artists were reluctant to speak out at length, posting either short messages on Twitter that carefully balanced support for young people and condemnation for the rioters, or publicising initiatives helping people who suffered in the looting and arson. Their reticence has drawn ire from other musicians, such as DJ Calvin Harris, who seemed to think the urban music scene should be making some kind of joint public appeal for calm in London's inner cities: these "role models", he tweeted, "need to speak the fuck up [and] help stop this".

Many of them have – and their words offer far more insight than most of the hand-wringing currently going on in Britain's desperately limited "public debate". The one key difference between the fulminations of politicians and media commentators, and people who live in the middle of riot-affected areas, was the lack of surprise. Everyone in the UK was shocked, but not everyone was surprised – this latter category seems to apply to Britain's urban stars, as well as young people I talked to on the streets of Tottenham on Saturday, as a double-decker bus burned in the background. "It's not just happened out of the blue," says Bizzle. "The kids have seen the opportunity to take the piss now – because they feel like they've been taken the piss out of their whole lives – but it's been going on for years."

For Professor Green, a top 10 artist, like Chipmunk and Wretch, and one of the MCs who has been most eager to illuminate the causes of the riots, it's a story of a country that has elected to forget about many of its young people. "What needs to be understood here is there is a lot of anger in the underclass, and a lot of the youth aren't quite sure where to aim their anger," he told me by email. "There are also a lot of underprivileged children who've grown up without boundaries, without the love, care and education a child should have. We grow up with less than most, but at the same time have everything we don't have rubbed in our faces; we're desensitised to drug dealing, drug taking, stealing and violence from the moment we are allowed out to play, as it exists on our doorsteps."

This idea of a country of divided cities is one that resonates for Bizzle, too. "People come to central London and think 'Oh this is a lovely place', but you go a couple of miles down the road and you see what's going on. London is not a happy place, and the world can see that now. Robbery. Arson. Theft. Murder: it's been going on for years, but the government's been looking the other way. I see the riots and looting as young people thinking 'we've got an opportunity to answer back to the government', even though it's the wrong way to do it – because it's not harming them, it's harming innocent people. But I think they're just frustrated, trying to be heard."

They're not the only ones – Bizzle has put his message directly to David Cameron before, and feels his warnings went unheeded. In 2006 he wrote an article for the Guardian calling him a "donut", for blaming knife crime on the influence of rap. "I read that article again for the first time in a while yesterday," he tells me. "If [Cameron] had paid attention to what I said, it would have been a whole different story right now. Because what I said was 'if you don't pay attention to the youth, it's going to get silly' – and look what's happening!" He cites his own song, Babylon's Burning the Ghetto, as an example of a record that carried a message. "I was saying this five years ago. They have to take us seriously, because we've got more influence and more input on the youth than they have." It will come as little surprise that he wasn't impressed with Cameron's holiday in Tuscany. "Your country's burning down, and you're in fucking Italy drinking tea, and eating croissants – for three days!" He pauses for breath, calms down. "But then the Conservatives have never cared about working-class people." His main accusation is one of wilful neglect. As he says in his song You'll Get Wrapped, speaking to the same "donuts" in parliament: "Have you been to where we live? Have you been to society? You can't point your fingers if you don't know what you're talking about".

For Professor Green, there's the same mixture of affection for his city and a sense of its challenges if you're not one of the lucky ones. "London is a wonderful place to grow up," he says. "The fact it's multicultural, the fact we aren't segregated, there's a lot of good that comes from this. The other side to it, is that for many people it is a tough and cold place to grow up. As a kid on Northwold Estate [in Hackney], for the most part we had to make our own fun. Nobody had much, and the olders we looked up to and spent time under the wings of were already some way involved in what most of us youngers one day would be. A lot of people went home to a less than ideal familial situation and there wasn't any avenue to voice the frustration born from this."

If it needs spelling out, no one has drawn pleasure from the riots. Professor Green sums up the mood: "To see the city I know and love in so much pain and despair is incredibly saddening. It's not really something that can be put into words." And yet, in remarkably speedy "breaking news" style, Britain's MCs and rappers are putting it into words – already. When I speak to Bizzle, he predicts "riot music" will soon be on its way, responding to what's happening. By the following morning, it's arrived. In only two days we have had Genesis Elijah's raw, captivating a cappella UK Riots: "We all came together last night/ for that, I'm grateful – maybe we'll call that a breakthrough." Bashy and Ed Sheeran's Angels Can't Fly seems a bit rushed, but then it presumably was, and features Bashy's usual thoughtful style: "Where I'm from, you don't see angels, man just see rainfall/ Slip and you could get a brain-full." Reveal's I Predict a Riot, with crushing inevitability, samples Kaiser Chiefs, but is otherwise powerful: "How many youths," he asks, "are in this to make a difference?" Meanwhile dancehall artist Fresharda's response, Tottenham Riot, calls for "more ghetto yout' [who] stand firm and stay strong/ planning dem future in education".

The most extraordinary of the bunch is also the most full-on. They Will Not Control Us, a snarling litany of dispossesion and rage against politicians, police and the media, will be a bit strong for some stomachs – and not only because of the wailing chorus lifted from the Muse track Uprising. By a little-known rapper called 2 K Olderz, it's nothing if not direct. "Dear Mr Prime Minister …" it begins, "was you travelling on London transport the day the bombs went off?/ How about you go and pay rent to the landlord, earn shit money doing a labouring job?/ We're living like shit in this country, while you've got your feet up living nice and comfy/ Well we know where the problem is, the people acknowledge this: stand up to the politics."

Talking about firing RPGs at parliament is not what you could call a constructive political response, but it would be ridiculous to say the song is not explicitly political – in its broad-ranging, nihilistic anger against all authority. While the nexus of the two may be contemptible, politics and criminality are not mutually exclusive: as one infamous Blackberry message stated: "Fuck the feds we will send them back with OUR riot … we don't need pussyhole feds to run the streets and put our brothers in jail so tool up, it's a free world so have fun running wild shopping."

It's a sensibility that arguably chimes with the bleak amorality of what's known as "road rap" – as opposed to grime, or UK hip-hop, all of which have distinct styles, musically and lyrically. Road rap is the scene that gave rise to Giggs, now signed to XL Recordings, and has flourished at street level via YouTube videos and CD "mixtapes" in places such as Peckham, Brixton and Hackney. It's relentlessly nihilistic, in a way that grime, with its roots in UK garage clubs, and lyrical contrasts between aggression and more witty, playful tracks about partying and relationships, never has been. On the classic track that brought Giggs to a wider audience, generally known simply as Track 9 freestyle, he describes a world in which "everyone's suit [is] the same colour as Batman's". It's an underground scene often believed to overlap with street-gang culture and so-called postcode wars.

"Harming one's own community is entirely mindless, but why would someone care for a community that doesn't care for him?" says Professor Green. So is it political? "They might think of this as an uprising, but the anger is misdirected and conveyed in such a way will not have any kind of positive effect. There isn't much sense to any of it."

If the mentality of some of the young rioters and looters is directed against authority figures, then despite what Calvin Harris might suggest, that includes their "role models" too. Wiley, widely considered the godfather of grime, speaking on the phone from a recording studio in Jamaica, where he is working on his new album, expressed a mixture of empathy and hopelessness.

"These kids won't listen to me. I wish they would, but they won't," he says wearily. "In London, they love you so much, but they can hate you in a click of the fingers. If I went down to the streets of Woolwich, to tell these kids to stop, and if they saw Wiley out on the streets right now … I'm like Jesus in this situation! If I was out there, they'd all be trying to crucify me, so they could say 'yes, we got Wiley!'.

"It could be 50 Cent, it could be P Diddy, it does not matter," he continues. "The way the kids see it, everyone in this stupid world is out for themselves, even the parents, and everyone just wants to have everything. I don't even think they're doing it because they want money, they're doing it just because they want to run the place."

So is this about trying to get a feeling of power?

"I hope it doesn't give them a feeling of power, because causing mayhem like that does not mean you're powerful. If the Queen does actually get serious and says right, army, go and lick down anyone who's not white who you think is causing a problem, and people start getting shot … these kids feel like they're ready to go against Robocop. They're testing the patience of the Queen, the government, the police. They're saying 'we're going to do what we want!' – and I'm thinking 'no you're not, because when the police get a grip on it, you're going to be either banged up, or dead'."

With the inevitable nationwide hunt for scapegoats, the articles blaming rap for its violence and promotion of a culture of entitlement are already arriving; as if this music was the only manifestation of aggression and rampant consumerism in western society. First among the self-appointed experts in the relationship between black culture and recent events, Paul Routledge, writing in the Mirror, blamed "the pernicious culture of hatred around rap music, which glorifies violence and loathing of authority (especially the police but including parents), [and] exalts trashy materialism and raves about drugs". At least Marge Simpson had the wit to criticise it for "encouraging punching, boastfulness, and rudeness to hoes" when she banned Bart from going to a rap concert.

More seriously, the steadfast refusal to understand, or accept the reality of inequality, underscores all of these criticisms: they have an "irrational anger against the world", wrote Routledge. David Goodhart in Prospect referred to the "nihilistic grievance culture of the black inner city, fanned by parts of the hip-hop/rap scene and copied by many white people", centred on "mainly unjustified" disaffection. "It's as if the routine brutalities and racist humiliations of 30 to 40 years ago have been lovingly preserved," he continued. According to Graeme Archer in the Telegraph, the young people of London's inner cities "speak in a completely made-up accent based on their idea of how gangsters talk", their heads full of "a musical subgenre that mixes blatant pornography with violent, egotistical lyrical content".

Rap music to blame again. For Professor Green, there's an entirely different connection between these debates and the riots: "It's ignorance like that of Paul Routledge that breeds the hate and contempt seen in people during this tragedy. Doing what I do now do has entirely changed my life, as it has done for many of my peers. Why would you want to further silence the already voiceless, and take away from people such as myself something that has had nothing but a positive effect on our lives?"

One of the most controversial accusations in the aforementioned articles is the suggestion of wallowing, the sense that people are somehow enjoying their own oppression, and would never have it any other way. If it does nothing else, the undeniably shallow electro-pop that has made ex-grime MCs such as Tinchy Stryder, Dizzee Rascal and Tinie Tempah wealthy superstars points to a pretty stern determination to rise above disadvantaged beginnings. As Lethal Bizzle argues – with a sincere flurry of "I do not condone this" caveats – people were most likely looting TVs so they could sell them to generate cash, and stories of people looting food, and even nappies, suggests a struggle to even survive, rather than a culture of amoral acquisition we see from our millionaire bankers as much as our pop stars.

So if the solution isn't banning rap music – which would be a pretty stunning move for a liberal democracy – what is it? "The key to all of this is education and understanding," says Professor Green: "I became a lot less angry when I learnt how to communicate, and began to understand exactly where my anger came from and what I was unhappy with." Wretch 32, too, says he wants to see an effort to "rebuild our communities by addressing people's issues, and creating more opportunities for our youth".

What about the Miliband-Cameron mantra of personal responsibility? It's not quite that simple, according to Bizzle. "People on my Twitter feed were saying to me 'well you turned your life around', and yeah sure, I did, but things were a little bit different back then. I remember going to community centres, and going on little trips, staying off the streets. My mum went to college and studied catering and she got a job straight away – she was fortunate then." So what's different on Britain's council estates now? "There are many ways to prevent riots, but the first thing is jobs – I mean fucking hell, where are the jobs? There are no jobs!" He leaves it hanging there for a split second, the frustration lingering on the phone line. "My little brother is 20 now, he's never had a job in his life – he's been trying to get a job for four years. And there's no logic at all in taking away the EMA and putting up uni fees: a lot of these kids who are involved in these riots, they're that age, where it's college, before going on to uni. Taking that away is madness."

"They need to start from ground zero, from these underprivileged kids, their unemployed parents," he continues. "They need to be working hands on with them, not sweeping it under the carpet, like it'll deal with itself, because now it's on their front doorstep." Meanwhile, money has been pouring into what used to be Bizzle's – and grime's – front doorstep, in the Olympic boroughs of Waltham Forest, Newham, Greenwich, Hackney and Tower Hamlets. "They've seen none of it," Bizzle protests, echoing the response of some east Londoners in the aftermath of the riots. "And now the government has to spend all this money to fix the country – if that money had been spent in the community, they wouldn't have had this problem in the first place."

On Monday night, DJ Logan Sama's weekly Kiss FM grime show ended symbolically with a tune by a young MC called Rival titled Talk That. First aired in April this year, it feels eerily prophetic all of a sudden, a grim answer to the questions so many are now asking – though too few will hear. It's a bleak description of drug dealing, violence, limited horizons and fatalism. "They want to know why there's all this anger, all this pain/ They want to know why I talk that violence, talk that slang …" Rival spits, before moving into a chorus that is sung with such stymied emotion that it's all the more poignant, because it's so flat: "I just say, 'It's all I know."

It's an age-old argument – one that most will never change their views about – but the case that music with morally unpalatable messages merely reflects reality, rather than glamourises or incites amorality, needs to be reaffirmed more than ever. If, as Martin Luther King wrote, "a riot is the language of the unheard", a result of "living with the daily ugliness of slum life, educational castration and economic exploitation", then this is Dr King's language rendered as art, and set to music.

Dan Hancox's new book Summer of Unrest: Kettled Youth is newly published by Random House