DJ Semtex, Dizzee Rascal’s man at the turntables, was affronted at the lack of clamour as the rapper left the stage before his encore. “Am I in the Isle of Wight or something?” the disbelieving deejay spluttered. The rapper’s hometown audience roared and whistled in response. A satisfied Semtex fired up the beats and Dizzee duly returned to the stage to resume the show.

The momentary hush didn’t signal lack of appreciation. Most likely it was breathlessness as we digested the impact of Dizzee’s knockout set. This was a fiercely authoritative performance by Britain’s best rapper, the sole figure of substance in a UK hip-hop scene that has struggled to translate underground vitality into commercial success.

Only 22 years old, yet with three albums under his belt, he opened with his debut single “I Luv U”, which came out in 2003, the year he won the Mercury music prize. Back then, he was a skinny teenager with a nervy, high-pitched rapping style. Now, he has grown muscular and his voice has deepened. Yet the sharpness he had as a tyro rapper from a deprived inner-city council estate hasn’t been blunted.

The set’s tempo was unrelenting. The music was a hardboiled blend of clattering beats and subterranean bass lines, with echoes of rave, UK garage and drum and bass replacing the soul and funk borrowings of US hip-hop. The rapping was fluent and fast, lyrics leaping from playground taunts – “Liar, liar, pants on fire” – to darkly paranoid threats, as if illustrating a world where children settle disputes with knives.

It was bleak stuff, but brilliantly depicted. A monstrously heavy “Sirens”, all distorted beats and sinister sirens, turned a tale of being pursued by the police into a trip into the inferno. Street credibility, an obsession in hip-hop, was the theme of a new song “Ghetto” in which the rapper declared that he didn’t “give a damn how street you are”. Another new track, “Dance With Me”, cleverly prettified his usual grimy sound with a disco beat and sung chorus.

“I’m in the world now, I gotta explore it,” he rapped at one point. He has the talent to take this quest for new audiences to extraordinary places – thought his deejay may draw the line at the Isle of Wight.