Thompson, the bassist whose presence was such a major part of the music of Pentangle and John Martyn, famously decided that the band he led in the 1980s and 1990s should be called Whatever because they drew on all sorts of genres and couldn't be pinned down unless to a style named after the band.
"Yeah, if we still had record shops the way we used to, Seckou and I would be in the Whatever section," says Finch, whose regular work outside the Keita-Finch duo generally comprises concert harp performances, such as the recital of Bach's Goldberg Variations in Turkey just after the tour that brings her and Keita to Edinburgh this weekend. "We've been called folk and world music and roots and other things but ultimately we just play what we play - and that's ever-changing. It's liberating when you've been used to learning a piece that has to be played in a certain way, which has pretty much been the way with me for most of my career."
The idea of pairing a classically-trained Welsh concert harpist with an African musician, whose core repertoire has been handed down orally through 50 or more generations, isn't so off-kilter, says Finch. Growing up near Aberystwyth, she was well aware of the Welsh folk song tradition from an early age. At school, music was geared towards the eisteddfods - festivals of music and literature whose origins can be traced back a similar distance to Keita's family history - and although she went through her grades on the harp (at a rate of knots, it appears) and progressed to the Royal Academy of Music in London, she also played piano and was quite familiar with the concept of improvising.
"My first inspiration was a Spanish concert harpist, Marisa Robles, who came to play near us in Lampeter when I was five," she says. "My parents took us to see her and I was hooked. She was this glamorous lady with a golden harp and I went up to her at the end of the concert and told her I was going to be a harpist too, as you do. But I started on a Celtic harp, which I got for my sixth birthday and which was a common sight where we lived, so there was a traditional music connection there. I was always experimenting, as well as playing the dots, through my teens. Then, when I moved to London, I hung around with the jazz students and played with their groups without neglecting the work I had to do to be a classical player."
A year into her course at the Royal Academy, Finch was asked if she'd accept the newly-created post of official harpist to the Prince of Wales, a role that led her to a double life as a scruffy student who got glammed up to play at the palace but also resulted in her becoming, through the attendant publicity allied to her obvious ability, a star performer with a schedule of concerts around the world and, in time, a recording deal with Deutsche Grammophon, no less.
The duo with Keita came about after a circuitous attempt to put Finch, who has also worked with Columbian folklorists Cimarron, together with the Malian kora master Toumani Diabate, who has a history of working with harp players including Scotland's own Savourna Stevenson. Finch and Diabate played concerts that went well despite their flying-by-the-seat-of-the-pants nature and, when their respective schedules couldn't be aligned, Keita, who had been a guest with them, stepped into Diabate's shoes.
The album they recorded, Clychau Dibon, went on to win fRoots magazine's Critics Poll Album of the Year Award 2013 and the duo has also won Songlines magazine's Best Cross-Cultural Collaboration Award 2014. The interest they've created has led to Finch looking forward to a summer that's different from her normal schedule, with appearances at Womad, Lorient Festival Interceltique in Brittany and Cambridge Folk Festival.
"This is great for me because these are platforms I haven't experienced before," says Finch. "Seckou's based in England, so working together is quite straightforward and we can slot things in as our diaries allow. I find the concerts with him quite relaxing and I hope that's the case for the audience - that they can come along and forget about things like tax returns for a couple of hours. People might think that coming to something spontaneous, where music can be worked up into a song during the soundcheck, is challenging for someone used to reading music. But I find the challenge is to keep the classical stuff going. When I finish the tour with Seckou I'll have to allow myself a few days to get back into my life as a classical musician."
Catrin Finch and Seckou Keita play the Usher Hall, Edinburgh on Sunday