O2 Arena, London This is slicker than their thrillingly chaotic early gigs, but the veteran New York hip-hop crew’s flows remain feral after 30-odd years O2 Arena, London This is slicker than their thrillingly chaotic early gigs, but the veteran New York hip-hop crew’s flows remain feral after 30-odd years R ZA peers quizzically into the O2 audience through a pair of impressively bejewelled sunglasses. “How many people in this crowd were born in the 70s?” he enquires, after an attempt to get