Jon Hendricks, London Jazz Festival, Ronnie Scott's

Another sold-out gig, another standing ovation, another memorable night. A sprightly 89 years old, the vocal pipes may not be quite so silky, but on the first of a three-night run at Ronnie Scott's, Jon Hendricks – dubbed the “James Joyce of jive” by Time magazine - still had the chops to show why he's considered one of the most original and influential singers in jazz.

Actually, to call this a gig sells the evening short by a country mile. Accompanied by a trio of vocalists - his daughters Aria and Michele, plus Kevin Fitzgerald Burke - this show was part family “git-together”, part musical “happening”. Embracing everything from hushed solos to the magnificently rich textures of the full quartet, we witnessed Hendricks scatting, playing the flute on a drumstick (“This is my flout. It's different from a flute. I flout convention”) and improvising the most ingenious bass and horn solos.

As part of the vocal trio Lambert, Hendricks and Ross, Hendricks is credited with being one of the pioneers of vocalese. "Er, what's vocalese?", I hear you say. OK, take any classic jazz album by Bird, Monk or Coltrane. Pick one of those really tricky, circuitous solos that darts around all over the stave. Now, try singing it. Not so easy, right? Here's the kicker: imagine not just singing the melodic line, but penning lyrics that fit every syncopation, every tongue-twisting triplet, every last melodic leap like a glove. And, crucially, singing those lyrics like it's the most natural thing in the world. That, in a nutshell, is vocalese. Done badly – we've all seen Jazz Club (Crazy!) - it's fist-gnawingly embarassing. Done well, it's one of the most free-flowing, graceful and breathtaking things in jazz. Tonight, we witnessed a true master at work.

Over two sets we were treated to a series of classic cuts from the Hendricks catalogue: “Desafinado”, which, despite never growing louder than a breathy whisper, emanated a deep poignancy; a towering vocalese version of Thelonious Monk's “Rhythm-A-Ning”, which Hendricks reworked as “Listen to Monk” on his fine album Freddie Freeloader (Hendricks on Monk: “His favourite word was mother. And that's only half the word”). Philip Larkin, you feel, wouldn't have approved. Ronnie Scott's, on the other hand, lapped it up; the perennially uplifting “Everybody's Boppin'” from the live album Boppin' at the Blue Note; and some deeply swinging nods to the Lambert, Hendricks and Ross repertoire including “Centrepiece” and “Moanin'”.

Hendricks was backed by the terrific Ronnie Scott's house band – pianist James Pearson, bassist Mark Hodgson and drummer Andy Watson – with the telling addition of US guitarist Paul Meyers, who's been on the road with the singer since 1993. Backing Hendricks will most definitely keep musicians on their toes, and the quizzical looks quota was as high as I've seen at a jazz gig (“What's he doing next? When do we come in? Why did I agree to do this gig?). But it was that spontaneous, flying-by-the seat-of-your-pants element that provided the evening's incendiary charge.

The encore, “September of my Years” (from the pens of Cahn and Van Heusen), was one of the most infinitely touching things I've heard all year.

• The London Jazz Festival continues until Sunday 21 November