Twenty-five years ago the Klezmatics were called the enfants terrible of the Jewish musical world.

Purists baulked at their alleged adulteration of east European klezmer. Others questioned their blending of leftist progressive politics with heimische Yiddish melodies.

A quarter of a century on, and the supposed rebels are justifiably hailed as the doyens of of 21st century klezmer (and a string of other genres).

In a sense they won the simple argument – Jewish diaspora music has always been an ever-changing mix of elements: by turns exuberant and poignant, eastern and western, a bastion of ancient traditions, yet open to the social changes of the day.

And while the Klezmatics are no longer all in the first bloom of youth, you couldn’t tell from the energetic and ever inventive performance at the Union Chapel in Islington.

'Two-and-a half hours later the audience emerged with a collective spring in their step, smiling as if they had each been given a musical flu jab to overcome the winter blues'

Certainly the crowd seemed pleased. Talk about a portrait in contrasts. Some 900 music lovers queuing in London’s October drizzle, gamely suppressing the anxiety that they might miss what they were longing to see.

Then two-and-a half hours later they emerged with a collective spring in their step, smiling as if they had each been given a musical flu jab to overcome the winter blues.

The occasion marked a relaunch for another daring institution that has remoulded the way people view, or even define, Jewish music.

That body, of course, is Britain’s own Jewish Music Institute. The concert marked the official relaunch of the JMI, and the JMI’s newly appointed artistic director, Sophie Solomon, was as much performer as co-ordinator.

She leapt onto the stage, violin in hand, like a female avatar of Nigel Kennedy, full of verve and attitude and a total bodily immersion in the music.

The Klezmatics proved the perfect foil and got the audience clapping along to her syncopated tongue-in-cheek composition, Swing.

Supporting the Klezmatics was the locally based and rapidly rising Balkan band, Monooka’s Caravan, who recently delighted crowds at the JMI's Klezmer in the Park event.

In fact, their pairing with the ‘Matics was perfect, as their geographical soundscape of Bulgaria and Romania melds naturally with Bessarabia, the focal point of quintessential klezmer.

Led by the charming Romanian-born, London-based singer and puppeteer, Monooka (aka Monica Lucia Madas), the Caravan consists of dulcimer (or tsimbl) player Cristi Vasile , as well as Meg Hamilton (violin), Matt Bacon (guitar) and Paul Moylan (bass).

They opened with La Ciolpani, a medley of Jewish and Romanian song, then a light-hearted Cirip-Cirip.

Next came a fantastic duo of bass and voice in a traditional Transylvanian doina, though updated with some pretty funky bass manoeuvrings.

It showed off Monooka’s vocal range and inflections to full effect. Ottoman Turkish and Greek influences shone through in the old Romanian song, Lelita Saftita, while a Wallachian gypsy-flavoured Saraiman won applause for a bazouki-like solo on the guitar.

Duly warmed up, the audience knew they were in for something special when, after the break, Klezmatics drummer Richie Barshay beat out a fearsome syncopated tattoo, and got listeners to echo him.

Still just 29 and already a veteran of the Herbie Hancock Quartet, he set the stage for a haunting introductory doina on tsimbl by Paul Morrisset, accompanied by Matt Dariau on kaval (breathy Turkish flute).

Then came the band’s rousing favourite, Klezmorimlekh, followed by the haunting Davenen and the cheeky Kats unt Moyz.

Speaking after the concert, Frank London, co-bandleader and trumpeter extraordinaire - said that everything came together; the band was inspired by the audience’s receptiveness, the lively dancers, and not least the Chapel itself, whose subdued lighting and wonderful acoustics really matched the music.