The favoured subjects for Os Racionais’ raps are government/police corruption, drug dealing, racism and favela life. Their experiences are pulled not from Grand Theft Auto and MTV but from growing up and living in some of Sāo Paulo’s most dangerous slums. They have cemented their position as the voice of the young, poor, usually black, favela dweller and chronicle the realities of life caught between crime and social exclusion.

Trouble seems to stalk them.

Their bust-ups with the police have been well documented, as have disputes with their record label. Last year they hit the headlines worldwide as a special concert staged in the centre of Sāo Paulo descended into rioting as the crowd grew impatient at their delayed arrival.

Arriving on stage in Vauxhall almost two hours late, violence soon ensued again. Barely two songs in the dance-floor erupted in fighting and it took repeated please for ‘calma’ and ‘respeito’ from promoters, security and the band alike before the show could continue. Continue it did however and those brave enough to stick it out were rewarded with two hours of Brazilian hip hop at its rawest.

By the endit was hard to tell who was supposed to be on stage, and who had merely fought their way up there, as a string of wanna-be MCs were invited up to join the group. Some were good (if anyone knows the name of the little Portuguese guy, post it below), and some were not.

The Racionais’ brand of hip hop is not beautiful; gritty raps are laid down over speaking busting, bargain, beats. And the beats are basic; DJ KIJay makes clever use of samples but for the most part the music is of the stripped-back, bounce along bleary-eyed to variety. It’s the words that are left to do the talking. Not ideal to crack the UK market but that was never the intention; this was an exclusively Brazilian affair.

Despite being able to hold their own against the best the US or the UK has to offer, and put shame to most, a true appreciation of Os Racionais requires Portuguese — not merely enough to order a caipirinha or an ice cold Brahma, but to really understand it, and to grasp the complexities of Sāo Paulo slang.

The Brazilian Public Enemy, as they are sometimes known (they are of a similar set-up, hail from a similar time and could conceivably be seen as the poor, black, Brazilian CNN) played all of their classics. ‘Fim de Semana no Parque’, ‘Pânico na Zona Sul’ and ‘Tempos Difíceis’ were among the best received.

The show ended with Mano Brown being dragged from the stage mid rap and being lifted onto the shoulders of the crowd from where he launched into two more verses. The music was far from beautiful and the lyrics may have passed me by but this was undeniably something special.