Ed Sheeran’s Galway Girl is playing in the background of the café where I’ve arranged to meet composer Sam Eastmond. Sheeran, followed by Taylor Swift. It couldn’t really be more incongruous. Eastmond’s music is the complete antithesis of this soft commercial pop.

If listening to Sheeran is the musical equivalent of having a warm, scented bath, then Eastmond’s big band sound is like being woken up at 5am by someone chucking ice cold water in your face. It’s unexpected, it’s challenging, and it’s not always comfortable. But it certainly gets your attention, and makes you feel more awake than you’ve been for years.

“What excites me,” he says, “is lots of people making a noise. Lots of people communicating. What I’m trying to do is blurring the lines between orchestrating and improvisation, making the improvisation part of the organic foundation of the writing.”

If that baffles you, then think of Eastmond’s musical inspiration as a Friday night dinner with everyone talking at once. He keeps a purple diamanté skull on his desk, to have someone to talk to when he is composing. His wife, who is not Jewish, was baffled when she first observed him with his mother. “She’d ask ‘Why are you always shouting at eachother?’ I’d say ‘We’re not shouting!’” For the first four years of marriage she couldn’t bear his favourite show, Curb Your Enthusiasm. “She just didn’t get it. ‘It’s just Jewish people shouting at eachother’” Luckily, she persevered.

I get the impression that Eastmond rarely curbs his own enthusiasm, in face he’s a huge ball of enthusiastic energy, which is both infectious and cheering. His biggest enthusiasm musically is the New York composer and musician John Zorn, famous in avant garde circles, and undoubtedly the leader of the Radical Jewish avant garde movement. “Zorn’s world is the radical Jewish music world, and I’m very much in the downtown diaspora here,” says Eastwood, glowing with evident pride and joy as he describes how his devotion to Zorn’s music eventually led to meeting the man himself, and being allowed to record two albums of music taken from Zorn’s Masada songbook. A third album is out next month.

For his latest project —BRIT-ISH — he’s assempled a big band of three trumpets, two trombones, a tuba, four saxophones, a guitar, bass, drums and piano, all played by musicians he knows and trusts. This makes the improvisation possible, because he knows and understands them, he can “set them problems” to which they can respond. “I’m writing soundscapes for them to play on top of and react to. A frame work. Some boundaries. A conversation between different parts of language.

“A lot of my music jumps from one field to another. Things are changing all the time. Sephardi groove to film noir, Mancini, the next moment. That’s where the interest is for me. Take a little line of music, a chink, and try and test it to breaking point. Pull it apart, deconstruct it, ask how much can I take out or add. You have a piece of music of 15 minute long, and the core of it is one little melody maybe 20 seconds long.”

Those problems, those short melodies for BRIT-ISH have the ambitious aim of telling our story, the British Jewish experience. This was the challenge that Eastmond set himself, when applying for funding, and then when he succeeded, working out a way to achieve. “I can’t talk about theBritish Jewish experience, but I can talk about a British Jewish experience.” He realised he would have to talk to other people, “I didn’t want to write a linear, sort of Charlton Heston bio pic…’This is the Story of the Jews of Britain’…I’m not interested, and who’s going to agree? We’re Jews, Agreement is not what we do.”

So instead he set out to talk to Jews about the British Jewish experience, looking for people quite unlike him (“Orthodox and drag queens, that’s who I don’t experience,” he jokes) Interviewees included Rachel Fink, head teacher at JFS, and the sociologists David Hirsch and Keith Kahn-Harris. His own community, Ealing Liberal Synagogue was another inspiration. From these conversations he created melodies, which were the basis for improvisations and orchestrations working with his musicians, most of whom are not Jewish.

This is, in part, because much of the Jewish music scene here is based around klezmer. Although Eastmond’s music is clearly influenced by and includes elements of klezmer, he’s wary of the way it can feel backward-looking. His music, he stresses, is about creating something new. He kicks against the sentimental streak that can creep into talk about stetl life. “There’s a reason why everyone was trying to get out of the stetl. Yes, preserve and celebrate its music but we shouldn’t want to return. It has that aesthetic. I think it’s dangerous.”

Eastmond grew up outside the mainstream Jewish community, living in Oxfordshire, the Midlands and Sheffield. His parents felt that science superseded religion, but his grandparents “made sure I know, ‘this is who you are.’ I always considered myself a Jew on a very conscious level.” He didn’t have a barmitzvah. “I’m still bitter about it. I remember the arguments. My parents view was that if we If we do nothing you can decide.” Now, he’s “a very ‘out’ Jew.” He has a star of David stud in his ear, a positively rabbinic beard and he wears tzitzit, although he doesn’t walk around Hounslow, where he lives, with them on show.

BRIT-ISH examines the British Jewish way of life, but Eastmond’s spiritual home is really New York. He’s frustrated by the tendency in our community to keep our heads down, and live in a bubble. He prefers the “American concept of dual identity” that means you don’t have to decide to subsume your Jewishness to fit in. “I think that’s destructive,” he says.

He’s aware that his music is not for everyone, “we’re on the margins of a niche,” he says, and that his opinions might ruffle feathers too. “Being totally honest all the time can be problematic,”, he admits, “but I sleep better at night.”

BRIT-ISH is featured in a concert at JW3 on October 17, along with the world premiere of Sam Eastmond’s Spike Orchestra’s Binah, from John Zorn’s Masada Book 3, The Book of Beriah, and the album launch of Sam Eastmond’s Gulgoleth. BRIT-ISH is a JW3 commission, and was one of the new works selected for The New Music Biennial 2019, an initiative of the PRS Foundation