There are moments tonight when I sit transfixed by the sight and the sounds of George Benson’s fingers flying about his Ibanez guitar. There are other moments when I wonder if the world’s most luxurious cruise liner is missing its star turn.

That is Benson’s career in microcosm.

As a guitarist, Benson is a master, his vivacious, nimble style often paired with the scat singing through which he acts as his own effects box. When he puts the guitar down and croons, which he does a lot, he is the musical equivalent of Formica. His popularity as a singer came about almost by accident: feted as a jazz player, Benson enjoyed a hit in 1976 with the album Breezin’ thanks to its solitary vocal track, This Masquerade. And he must have really enjoyed it, because that’s what he’s been doing ever since.

Heard live, his bland, glutinous ballads give me the sense of playing the embarrassed gooseberry at an intimate assignation between Benson and his audience. They’re having a Moment; me, I hardly know where to look. But when he picks up both the guitar and tempo, songs which were briskly inoffensive on record leap into colour.

His reading of Donny Hathaway’s The Ghetto rumbles with slinky menace. Breezin’ is loose, feather-light and dusted with nimble fretwork. He reinvents LTD’s Love Ballad as glorious, swirling Philadelphia-sound disco. His biggest UK hit, Give Me the Night, sheds its tippy-tappy Quincy Jones sheen and shimmers with the exuberant neon vibrancy of the city after dark.

The finale, his celebrated version of the Drifters’ On Broadway, is steel toe-capped and flick-knife sharp. It’s hard to credit this is the same artist who half an hour earlier made me feel as if I were chewing my way out of a giant six-tier wedding cake.

• At the Old Royal Naval College, Greenwich, on 25 July. Box office: 020-8269 4799.