What do you get when you combine the celebrated classical clarinettist Emma Johnson with the serried ranks of Klezfest Jewish music practitioners? Air on a K-String might be one answer. Yet the truth, as revealed at the Jazz Café last Wednesday night, was considerably more dynamic, surprising and downright funky.

London-born Johnson was young musician of the year in 1984; as a soloist she has entranced audiences on virtually every continent, and she has recorded some 20 discs, of which her recent “Mozart Album” rode high on the classical music charts for several weeks. So how would she cope with the krechts (sobs) and syncopations of klezmer? Like a seasoned veteran, it proved. With her instrument’s rich chalumeau register and her brilliant sense of timing and vocal nuance, it sounded like she was born playing klezmer.

Emma hit the stage when the atmosphere was already electric, and proceeded to launch into a friendly cadenza duel with American klezmer trumpet maestro, Frank London, that had the audience on their feet.

London himself provided the Balkan-tinged punch that drove up to twenty enthusiastic fiddlers, accordionists and tootlers on a packed stage. A leading light in the klezmer revival and kingpin of the legendary Klezmatics, he also revealed a penchant for that other element of the klezmer universe – the badchan, or jester/ compere.

On hearing a breakneck solo introductory solo to the classic, “Fun Tashlikh”, by London-based Paul Tkachenko, London confessed to being “instrumentalist” when said how embarrassing it was to witness a tuba player who could play faster than other instruments. He added that it was probably his 17th bought on ebay.

Nor was this the only instrumental innovation: Francesca Ter Berg on cello, Andreas Schmitges on electric mandolin (more incisive chisel than Hendrix-like axe) and Guy Schalom on darbuka and other percussion, all proved how adaptable the klezmer form is.

Schmitges was actually the dance instructor of one of the three strands of the preceding Jewish Music Institute (JMI) klezfest meet in London, the others being instruments and voice. And it was Polina Shepherd, the singing tutor, who provided another highlight with an amazing soaring rendition of a Yiddish tune telling the story of the Baal Shem Tov happy in the wind and cold, sun and heat. If you thought that that was the besht, it only got better when she followed with an alluring jazzy melody, accompanying herself at piano. Meanwhile graduates of the dance classes wended conga-style through the audience (forcing this particular writer upstairs).

Three bands set the scene for the exciting evening, the first being the British-based trio Kavonah (clarinet, accordion and cello) with their subtle variety of sombre and jolly sounds. Next came a Czech group whose flute, harking back to authentic klezmer roots, provided a gentle, lyrical underlay. Jokingly the bandleader referred to the irony of their singing a klezmer ditty about the sea – when landlocked Czech Republic has no sea at all. Yet while things were quiet till then, the audience came alive for their rendition of the classic rousing Ma Yofus.

A dramatic change of tone and hemisphere followed, when Klezmer Four, from Brazil, took the stage. Actually there were just three players, because as their ebullient lead singer explains, they come from a third world country, could only afford three tickets, so abandoned the pianist in favour of the promoter!

A stirring rendition of Chad Gadya preceded a gentler song in Ladino, to evoke Sephardi roots, another heritage twinned with the more Yiddish-inflected klezmer oeuvre. “Four’s” excellent violinist thrilled the audience when playing at double speed; and the Latin-tinged guitar of Marcello Cohen provided the perfect counterpoint to the singer who took to percussion. A most unusual variety, however, as she admitted – a cheese grater played with thimbled fingers – but then, as she explained, “when a Jewish mother is asked to provide percussion, she goes to the kitchen”.

Another curious yet equally effective blend of cultures was evoked when another singing student trilled in Yiddish to a reggae/dub backbeat. Full of tribal “call-and-response” effects, this new blend with klezmer seemed to gel quite naturally. Then Trio Yas – Guy Schalom on drums and percussion, Christian Dawid on clarinet, and Sonia Moricke on accordion – introduced a more intimate sound, exploring different rhythms and moods.

Similarly poignant was Ilana Cravitz on violin, who introduced a song composed by a late friend and much loved JMI alumnus. In a collegial atmosphere the grand band gathered for the final session to play tunes composed by a past teacher, the Israeli Musa Berlin. Merlin Shepherd, klezmer clarinet wizard extraordinaire, joined the for a guest appearance, where his ever-rising arpeggios and woodwind yelps spiced the musical melange yet further. Then seasoned performer that he is, Frank London restored a fitting sense of calm and repose for the final piece, an only vaguely klezmer-tinged rendition of Leonard Cohen’s anthemic “Hallelujah”. In all, a remarkable evening that had all the energy of the Jazz Café’s usual fare; plus the added aplomb of Johnson’s classical virtuosity.