It's a straightforward concept used by everyone from Brian Wilson to the Wu-Tang Clan: get a legendary artist to perform in full one of their legendary albums. Public Enemy have done it before, playing 1988's It Takes a Nation of Millions to Hold Us Back on stage three years ago. They're supposed to be doing it again tonight, with Nation of Millions' equally revered followup Fear of a Black Planet, but they clearly have other ideas.
"I'm not comfortable with the concept," says Chuck D. "So we're going to perform Fear of a Black Planet remixed." This turns out to mean they're not going to play Fear of a Black Planet at all. Instead, you get what you suspect is Public Enemy's standard live show, with the occasional shout of "Fear of a Black Planet REMIX!" thrown in.
It all raises some interesting questions, not least as to whether this constitutes an iconoclastic bucking of an increasingly tired trend, or just ripping fans off. On the one hand, what follows is a great show. Once a menacing, armed expression of black militancy, the Security of the First World, as the band's "dancers" are known, look a little chubbier these days: they're more the Security of the Second Helping. But Public Enemy's music has lost none of its potency: Welcome to the Terrordome thunders forth, Bring the Noise sounds flatly amazing.
You get a lot of talking between tracks: thought-provoking if it's Chuck D raging about the recent riots, and a bit wearying if it's Flavor Flav plugging his career as a reality show stalwart. Now in their 50s, the pair remain kinetic: it might be the umpteenth time they've been required to roll out Fight the Power, but their performance never feels perfunctory.
Still, if you'd paid £25 to see Public Enemy play Fear of a Black Planet and ended up watching them do a track off 2007's How Do You Sell Soul to a Soulless People Who Sold Their Soul instead, you might feel a little aggrieved. Or you might note that it's Public Enemy, hip-hop's complex, thorny, self-styled Prophets of Rage: they never pretended to be a branch of the service industries.