Had the posters named those rumoured to be coming, it might have been a different story. But in north Liverpool – where word of mouth had yet to convey what was coming to town – Africa Express was barely a source of intrigue. The latest instalment of Damon Albarn and friends’ musical adventure sold out only on the night. Even Chico & the Cheeky Girls met with greater advance interest when they played here a couple of years ago.

When it comes to seven-hour musical extravaganzas, there’s usually something to be said for knowing what you’re getting for your money. But Africa Express’s successes to this point have all been predicated on the belief that the magic happens when you leave your comfort zone behind. Over seven chaotic hours, the best moments occurred when musicians and audience united in that realisation. Richard Archer, the Hard-Fi frontman, gazed on in amused awe at the Algerian rai star Rachid Taha as he daubed the group’s version of The Cure’s Killing an Arab in appropriately Middle-Eastern colours.

Therein lay a recurring theme. British artists would come on and do something that they had rehearsed, and their African counterparts would do something spontaneous and extraordinary with it. After coming on to play the clipped Cossack pop of Take Me out, Franz Ferdinand and their new chum Baaba Maal were reduced to delighted sidemen as Mali’s Bassekou Kouyaté divined miraculous intricacies from the strings of his ngoni and Maal’s drummer thumped out an astonishing display on the tama.

Familiar faces went down predictably well – and there was no shortage of them for a version of Gnarls Barkley’s Crazy that featured Taha, Maal, Terri Walker and a stunning beatboxing display from the Roots’ Scratch. No less heartening was the reaction meted out to musicians – in particular, the beatific acoustic blues of Senegal’s Wasis Diop – of whom much of the audience will not have heard previously.

However, for one increasingly inebriated Africa Express player, such understated delights had long been since left behind as the show reached its conclusion. In two weeks, Damon Albarn turns 40 – but at 3.05am, there was a present for which he could no longer wait. As Taha and his band whipped up a percussive desert storm, he barked Rock the Casbah in the manner of someone who wouldn’t rest until his request had been granted.

By the time 25-odd people lurched on to the stage to join in with Taha’s rai version of the Clash song, the lack of night buses and, no doubt, the irate texting of babysitters forced many to leave. On the way out they may have noticed another poster – for an imminent cage-fighting event – which promised “a gladiatorial spectacle without parallel”. Should the Africa Express charabanc ever roll this way again, it could do far worse than lift those words for its own posters.

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