The popular image of Stephane Grappelli is of a cherubic Frenchman, violin tucked under his chin, playing swinging jazz of the I Got Rhythm era and improvising with stylish verve. It’s not an image that easily accommodates Grappelli having a ball with the darkly urgent riff from Bundles, a Soft Machine composition from the English psychedelic band’s jazz-rock period.

This, though, was what could happen in off-duty moments in the late 1970s after John Etheridge, who had not long before replaced Allan Holdsworth in Soft Machine, found himself in Grappelli’s group. Indeed, Bundles, on which Etheridge was apt to turn his guitar volume up to eleven and let rip, played a part in his being invited to join Grappelli.

For Etheridge, whose Sweet Chorus tribute to Grappelli is one of the headlining acts at Dundee Jazz Festival this week, playing with Grappelli was as likely back then as lottery win and if it hadn’t been for a friend of Diz Disley, the rhythm guitarist who revived Grappelli’s career, seeing Soft Machine on television, it probably never would have happened.

“I got a phone call out of the blue from this bloke with a Yorkshire accent,” says Etheridge, whose tales are peppered with rich impersonations. “And this guy says, I’ve heard you’re a great young guitar player and I’m looking for someone to play with Stephane Grappelli, can I come round? Of course, I was thinking, really? Are you sure? But I said YESSS. So Diz comes round. I didn’t even have an acoustic guitar at the time but we played half a chorus of Sweet Georgia Brown and he said, Great, come to Hamburg. We have a TV gig.”

So began an initially unnerving experience that involved an interminable drive to Germany in the dead of winter, in a car with no heating, followed by Etheridge, on arrival at the hotel, being told to go and sit in his room. Eventually, after what seemed like days, Disley appeared and took Etheridge shopping for stage clothes because they couldn’t “have a scruff like you onstage.” A fierce red shirt and an Alan Partridge-style medallion purchased, neither being Etheridge’s choice, they repaired to the hotel where more waiting ensued.

Finally, Grappelli was ushered into Etheridge’s room with a face like thunder and much Gallic disdain.

“He wouldn’t look at me and as he was rosining his bow he said to DIz, Ask him if he knows Them There Eyes, and he proceeded to count it off at this ridiculous tempo,” says Etheridge. “So I played what I thought were the chords and Stephane snorted, What is that horrible chord? Then he said to Diz, ‘Ask him if he knows Manoir des mes Reves and tell him to accompany me.’ I’m trying to follow him and thinking, I’m in Soft Machine, nothing’s going to come of this. Then Stephane played You Are the Sunshine of My Life and told me to take a solo. I knew that one and I just went for it, and finally he looked at me. He stopped playing and said, ‘I like what you’re doing. It’ll amuse the tourists.’”

And that was Etheridge in the inner sanctum of a musician whose legendary partner, Django Reinhardt, had been one of Etheridge’s formative influences as a guitarist.

“Hank Marvin was first but then a friend of mine said, you’ve got to hear Django,” says Etheridge. This friend’s dad was a guitarist and he had Django’s records, which was rare at the time. There was only about one Django album available in 1963. So we listened to the records and played Sweet Georgia Brown, not very well, on our guitars. Then Eric Clapton, Jimi Hendrix and John McLaughlin came along and they made a big impression but I’d always go back to Django.”

With Grappelli, Etheridge was encouraged to be himself. He didn’t want guitarists to play the rhythm heard on the Quintette du Hot Club de France recordings and although he dismissed himself as an old square who couldn’t change, he was intrigued enough to try out a Soft Machine tune or two offstage.

“Not long after I left Stephane jazz seemed to come to a stop for a while in terms of development,” says Etheridge. “It was a case of choose your era and play in that style. And that was anathema to me.”

With Sweet Chorus, which includes violinist Chris Garrick, now best known for his work with the hugely popular Budapest Café Orchestra, Etheridge plays tunes associated with Grappelli, as well as originals, and tells a story or two, but it’s not about looking back, he insists.

“The important elements in jazz, for me, are spontaneity, improvisation and the spirit of adventure,” he says. “Sweet Chorus is my personal tribute to Stephane and the best way to honour him is to be like him and play in the moment.”

Sweet Chorus plays Gardyne Theatre, Dundee on Thursday, November 19. For full details of Dundee Jazz Festival, log onto www.jazzdundee.co.uk