There are times during the second of Shuggie Otis's two concerts in London when you can close your eyes and almost imagine that you are at a Shuggie Otis concert. This disconnect between what we were expecting and what we are watching is only to be expected. The son of Johnny Otis, "the godfather of rhythm and blues", has never fronted a show in this country before, and it is now 38 years since he released his slow-burn cult psychedelic-soul classic Inspiration Information.
Still, things are apparently an improvement on the first night, when problems with his guitar amp are said to have shaken this ever-reticent front man, who is still visibly shaking as he takes the stage tonight.
Before that, his six-piece backing band of veteran LA session dudes have worked their way through a 10-minute version of the standard "Comin' Home Baby". There have been band introductions – never a good sign this – before the person we have come to see has taken the stage.
When Otis does finally plug in, the music is immediately transformed into something altogether funkier. His wah-wah guitar playing is subtle and extraordinary; a delicate shade of purple in a sea of clunking blues. Suddenly, there is a glimpse of the prodigious talent that earnt Otis a place in his father's touring band around the time he hit his teens. At last, it is possible to connect the frail and shy man in front of us to the musical visionary who created that classic 1974 album.
And then he launches into the title track and everything almost falls into place. Almost. Because, as the music starts to gel, Otis's voice falls just short of the high notes and we are forced, again, to separate our reality from our expectations.
The strange thing is that, while we have all come to hear the paisley pop which predated Prince, it's the bluesier numbers that better suit what is left of Otis's voice. And though usually a singer crying out "Slow blues in C" would be my excuse to start locating the fire escapes, Otis's mesmerising guitar playing prevents that from happening.
Neither triumph nor disaster, these warm-up shows for bigger things to come next year will neither enhance the legend nor damage the reputation of Otis.
But there is one moment tonight that is unforgivable. It comes during the title track of the newer material that will be released as an album next year, "Wings of Love". Otis is at ease, conducting the players in a thrilling and unpredictable intro. His voice has found itself; his eyes are closed and he is lost in this music from his future, which is clearly more satisfying to his soul than merely replaying his precocious past.
Suddenly, someone in the crowd takes a picture and the band leader and trumpet player Larry Douglas shouts, while Otis is still singing, "No flash photos. Leave our integrity intact."
The gentle, soulful, sensitive, slightly shambolic Otis pretends not to notice. But here's a suggestion for him: if you want to keep your integrity intact, Otis, and soak up the huge vat of goodwill there is for your psychedelic and pioneering past, next year hire a sympathetic group of young musicians.