Ahead of Steve Reich's appearance at Bloc in the afternoon tomorrow, Leo Chadburn called up the composer for a second conversation about how he interacts with other musicians and musics. Radiohead revelations!

Steve Reich is now such a well established composer that it's increasingly difficult to think of him as a musical firebrand. His inclusion in this weekend's Bloc festival line-up, however, is a timely reminder of the repercussions his innovative music has had not only in the classical sphere, but also in dance, pop and electronic music.

Now halfway through his eighth decade, Reich is more philosophically engaged than before with the continuum of music history. He is at his most gleefully animated when name-checking musicians as widely spaced in time as the late 12th century composer Pérotin and 20th century composer Stravinsky. More surprisingly, he's also currently fascinated by the music of Radiohead, following a meeting with Jonny Greenwood last year. The result of this connection, a piece on themes by Radiohead for the London Sinfonietta, is not finished and not due to be performed until Spring 2013, but he is brimming with enthusiasm for it. It seems to be an interesting time for Reich, a moment of flux as he contemplates his own wide-reaching influence and place in the musical 'canon', whilst subtly challenging and evolving his own working methods.

Reich will be appearing at Bloc with the New York ensemble Bang on a Can All-Stars, whose own 25-year-long career is based on a formula of 50% Reich-inspired loops/minimalism, 50% rock music gesture. They will be performing a wide selection of Reich's more 'portable' music, ranging from his 1972 masterpiece of musical economy Clapping Music, to the 2008 piece 2x5, scored for a guitar-band line-up playing against a pre-recorded version of themselves.

The line-up for Bloc is very striking, in that it's entirely dance and electronic musicians, with the one exception of you and Bang on a Can.

Steve Reich: Well basically, if a venue or sponsor is interested in my music, I'm happy to be there. That may be the Barbican or the Southbank Centre or, as in this case, a rock festival. And, as you know, I've been involved in all shades [of music]. It all goes back to when I was a kid, a teenage drummer and going to Birdland. When I was going to Julliard, at night I'd go to hear John Coltrane play and studying in California with Luciano Berio again I'd go to hear jazz in the evening.

Then later, playing in London in 1974 with my own ensemble, after the concert a young man with long hair and lipstick came up and said, 'hello I'm Brian Eno' and I thought, 'poetic justice!'. Things don't always work out so ideally, but I've been very fortunate in that my music has reached these people. Like attracts like. I'm someone who likes Stravinsky and Bartók and Bach and BeBop, so that's what's coming back at me.

Your interest in music from many genres has resulted, in turn, in those genres being influenced by you...

SR: It's been going on for quite a while. Eno has talked about the influence of my early tape pieces on his work. He's done marvellous things and if I've contributed to that I feel very good about it. Then David Bowie, who was at the performance of Music for 18 Musicians in Berlin in 1976 and again in 1979 when we performed it at the Bottom Line club in New York.

In London in 1992, I was being interviewed by one of those pop keyboard magazines and the interviewer said, 'what do you think of The Orb?' and I said, 'what is The Orb?'. So he gave me the CD of 'Little Fluffy Clouds' [which sampled Reich's 1987 piece Electric Counterpoint]. Now, you see, Eno and Bowie had been influenced, but these guys had just took the music! I had been aware of sampling but I hadn't encountered any where my music was involved before. But, by not getting hot under the collar and just being pleased that it happened, everything worked out. Then four years later the Reich Remixed album came out with a whole bunch of still younger DJs contributing. And that kind of thing has continued.

Then last year in Krakow, Jonny Greenwood performed a new version of Electric Counterpoint. We got talking and I was struck by what a nice and interesting musician and human being he is, so I felt inclined to check out Radiohead. So I'm now in the latter stages of writing a piece called Radio Rewrite, which will be premiered in London in March 2013 by the London Sinfonietta - a famous rock group!

When we spoke last year, you'd just begun writing the piece for the Sinfonietta. At that stage there was no suggestion it was going to be based on themes by Radiohead. The concept changed?

SR: Yes, the whole thing changed. When we spoke before, my idea was that there would be 13 musicians on stage playing against a recording of themselves, like a giant counterpoint piece. I tried working on it, and everything I did was terrible. I started trashing this and trashing that. Anyway, the trip to Krakow and meeting Jonny Greenwood made me think, well, this music really interests me. What if I took these songs, 'Everything in its Right Place' and 'Jigsaw Falling into Place', and used some of the harmonies, some of the bass lines, some of the melodic material, but going my own way with it, using that material as a starting point, a stimulus. Sure enough, it worked. You know, you go where the energy is. So now there's about 15 minutes written out of a piece which will eventually be an 18, 19, 20 minute piece.

It strikes me that it's a quite traditionally classical music thing to do, in a way. So many composers in the past wrote sets of variations, or 'fantasias on a theme' of other composers' music.

SR: Exactly! This is the norm in the West. This isn't some aberration, or someone trying to cater to another audience. In the Renaissance, every composer had to write a 'Missa L'homme Armé' - a setting of the mass based on the melody of 'L'homme Armé'. What is "L'homme Armé'? It's a folk song! It was like a musical challenge for them. Going on, Haydn used drinking songs in his 104th Symphony, Beethoven used folk song in his 6th Symphony. And you can't separate Bartók from folk - it's in his bloodstream. Charles Ives - you hear the hymns he used to play as a church organist make their way into his concert music. Kurt Weill - his music is pure Weimar cabaret, but he trained with Busoni. Or George Gershwin - one of the best composers we ever produced…

What I'm doing, and many composers are doing, is returning to this normal way of writing Western classical music. It's just that now notated music and non-notated music are listening to each other and learning from each other and enjoying it.

Outside of your personal relationship with the band, what is it about their songs, their actual musical material, that makes it suitable for this kind of treatment?

SR: Well, it's brilliant, absolutely brilliant songwriting. I saw a black and white video of them rehearsing 'Jigsaw Falling Into Place' and what struck me was not only that it was a beautiful song, but that the band are so committed. There's no showbiz, just musicians communicating very directly. There's no fudging that.

In both those songs, the chord sequences are very interesting, These are beautiful tunes and I can't improve on them, so I've written my own piece, but sometimes something comes to the surface which reminds you very clearly and sometimes not so clearly of what they do. I mean, it's scored for flute, clarinet, two vibraphones, two pianos, string quartet and one electric bass, which only appears in the first and last movement, so it's not at all a rock piece. Now, '2x5' is a piece that wears rock on its sleeve, so to speak, because it's written for those instruments, but in Radio Rewrite, if you didn't know the original material, rock & roll wouldn't cross your mind. You'd just think, "this is a piece by Steve Reich that I like, or don't like."

Interestingly enough, if you go to see There Will Be Blood and hear Jonny Greenwood's score for that film, you'd think the composer was some guy who'd been listening to Messiaen. I don't think anybody would think it was written by a rock player. We're in an interesting situation in which people are interested in different things, so they do different things.

Is this piece a one-off, or is working with pre-existing musical material going to be a new direction for your work?

SR: Well, my piece Proverb was modelled very specifically on Pérotin's Viderunt Omnes. I had the organ music on the piano whilst I was composing it and you can hear that. I've also done something that very few people have heard yet, because it hasn't been recorded - a two piano version of Sondheim's Finishing the Hat, because I really love that musical [Sunday in the Park with George]. My version is unmistakably Sondheim, more Sondheim than Reich in fact, but it has shifting metres and two pianos, because I have to have my interlocking canons. So Radio Rewrite is actually the third piece of mine modelled on some other music material.

Would I do something like that again? Well, sure, why not? As you noted, this is a perfectly natural thing to do. You think of Stravinsky's Pulcinella, which is entirely based on music by Pergolesi.

Pérotin, Sondheim, Radiohead - it's a broad selection of music you're drawing on. Are you able to spend much time listening to new music these days? Do you keep up with contemporary jazz, for instance?

SR: No, not really as much as I'd like. I have an enormous stack of CDs to listen to, but I'm a slow composer and there are a million other things which eat up my life.

Back to the appearance at Bloc, what music will Bang on a Can be playing this weekend?

SR: I'll be performing Clapping Music and, of course, Bang on a Can will play 2x5. I'm hoping that they'll also perform Piano Phase/Video Phase, which is a fantastic version of Piano Phase [originally composed in 1967] prepared by [percussionist] David Cossin, in which he plays a sampler with drum sticks against video projections, but behind a screen so you only see multiples of his arms, like Shiva! The video is a perfect 'hand in glove' visualisation of the music. I think they'll also play two of my 'Counterpoint' pieces, New York Counterpoint for clarinet, and Cello Counterpoint.

I interviewed [Bang on a Can co-director] David Lang earlier this year and he talked about his concern with the political aspects of his music-making. It made me think of your music, which has often addressed political issues very openly and even-handedly. Do you think it's important that musicians should be politically engaged?

SR: Absolutely not. I think it's important for musicians to do what they love to do. Because if they if they don't, we just end up with something concocted, something that has no heart: agitprop, and who needs that? There's no 'should'. Do what you want to do, because in the long run you and everybody else will be happier for it.

Issues have a way of coming and going, in fact they come and go at an alarmingly rapid rate, so attaching yourself to an issue means that the issue will pass and the music will pass with it.

So if people listen to Come Out today, they probably don't know anything about the Harlem Six [Come Out used a tape loop of an interview with one of a group of black teenagers accused of murder following the Harlem Riots of 1964]. That piece is nearly fifty years old, but there are still kids interested in sampling it. People said, 'oh it's a civil rights piece', and indeed it was - the premiere was a pass-the-hat benefit for a retrial of the Harlem Six, but that particular battle was won a long time ago and nobody really knows or cares about its history. The piece stands because musically it really gets to people. In a piece like [September 11th terrorist attacks documentary piece] WTC 9/11, I was obviously personally involved, and it was important to me. But if I don't do a good job musically, who cares? The same thing with Different Trains [1988 Holocaust documentary piece] - it's very autobiographical, but if it's not really well done people are going to say, "well, that's nice, what else have you got?". What I'm saying is that if you really care about an issue, you better write the best music you possibly can. Then it might just survive. That would be my advice to young composers.

You started out as a young composer yourself in the 1960s. All these years later, how do you see the outlook for today's young composers and musicians?

SR: The computer has basically killed the record industry as we knew it and the idea of becoming a superstar through your recordings is… unlikely to say the least. So what that's done is put the pressure on live performance, which is really, basically what music is. And the wonderful thing is that people come to concerts. There's a lot of interest in live music, which is the way it's been since we've been on this planet. So, on the one hand, that's reassuring. The bad news is that, in terms of becoming known enough so you'll be offered the gig in the first place… say you're a young kid, you get your stuff on iTunes and then… who cares? There are millions of tunes on iTunes! So if I were that age, I can see how it would be difficult to get things done.

But musically, right now there's a kind of anything goes and there are all kinds of styles as opposed to when I was a music student (at least in the classical world) when there was one way - the Boulez/Stockhausen/Cage way. Today there's all kinds of ways. Some people are writing music that sounds like Sibelius, other people are writing music that sounds like Radiohead, some people are writing music that sounds like me and some people are still writing music that still sounds like Boulez and Stockhausen. You name it, we've got it. Whether that's a better situation or a more difficult situation is hard to say.

A bright future for creative music then?

SR: Ha! I've given up the prediction business!