In his big, sunny, west London studio, the musician, composer, producer, artist and ideologue Brian Eno is listening to the freshly delivered CDs of his new group's rehearsals. The track currently playing is a big-smile-on-the-face chunk of jazzy, funky, ultra-tight improvisation, and, while he listens, Eno is shouting out the chord changes from memory. "F!" he exclaims, as the whole piece takes another rollercoaster dive on its thunderous, exhilarating journey; and then, "Oh, please, let it be G sharp. Please, please, please..."
The track revs up again, and, "Yes!" he cries, "G sharp!" One of his assistants suggests that he should call out the chord changes as part of the forthcoming concert in Portugal, Eno's first full-blown performance since about 1975 not counting a one-off show in Bonn in 1998 (with his current collaborator, J Peter Schwalm) and a piece for the blessing of a Japanese temple.
"Actually," he replies, "the only thing I'm sure about is that the whole band have to wear suits."
Even during a rehearsal session, the music has a wit, style and muscularity that is like a summation of Eno's musical career to date. You can spot the thrilling acceleration, for instance, of harder numbers from his first solo LP, Here Come the Warm Jets, made back in 1973 after his departure from Roxy Music. And then there's a hint of his febrile, nervy post-punk classic My Life in the Bush of Ghosts. It is remarkable how not one of Eno's records, when heard now, has dated in any way; together they represent a canon of work that confounds the distinction between pop music and experimentation, and the proof of their artistic success lies in the texture, sheen and composition of their eternal newness.
Eno being Eno, of course the music world's best-known futurologist all the material he intends to perform in Portugal will be brand-new. He is an artist who is famously uninterested in referring to his own past, except in terms of how it may inform new work. (About the current Roxy Music reunion tour, for instance, he simply says, "They were always a good band, but I was only with them for two albums.") Now, having recently released the hugely acclaimed Drawn From Life LP, in collaboration with the German DJ and percussionist J Peter Schwalm, there is the opportunity for Eno to develop the ideas brought together on that record, rather than simply perform it.
"The new record is quite performable," he says, "and I haven't done anything performable for quite a long time. There would be no point standing in front of an audience and doing Music For Airports, for instance that would be rather like those performances you saw in the Sixties, where they just switched the tape on and sat there looking serious while it played. I went to quite a few concerts like that.
"But the new stuff seemed as though it could be performed, in a kind of chamber version. Also, I made a rule that I only wanted to play in places that I wanted to visit anyway nice venues, nice cities. And then I thought, I don't want to perform this record! It's going to be a nightmare trying to recreate something as complicated as this. Then I realised that the reason why I had agreed to perform it was because I wanted to find a way of writing some new songs. So Peter and I put the band together, and almost immediately started making new material. So I'm doing a lot of composing up-front, and I'd love to end up with a new album that sounded pretty live, all of new material."
From his earliest solo pieces and collaborations (notably with Robert Fripp), Brian Eno has been recognised as a composer and musician who delights in conflating the ideas and practices of different intellectual strands and artistic disciplines. The fact that he has produced multi-million selling LPs by U2 and James can be seen as a practical demonstration of his astonishing originality as a creative facilitator and conceptualist. But his real interests reaching out through music to moral philosophy lie in the broader, pan-cultural applications of creative thinking. His installation pieces, for example, combine sound, light and sculpture in a way that suggests a practical notion of civic art; he would love to install pieces in airports or hospitals, places where people enter anxious states of minds. In this much, Eno is a futurologist whose roots are in the politicised spirit of enquiry, social humanism and intellectual open-mindedness that emerged in the late 1960s when he was still an art student at Winchester.
"There's a type of artist who believes in a system 'the system says I have to do this.' That was really my falling out with a lot of experimental music which is, of course, where I got a lot of ideas from, and I have to give full credit to that tradition. But what I didn't like was the lack of any feedback to reinform the process there were just the rules of the piece and they were carried out regardless. This seemed to me so unempirical, so unpragmatic, so pointless. Whereas I always think: make the system, make the rules, and then see whether you like it. And if you don't, change the rules."
When Eno cites contemporary chart music as being dominated almost entirely by the possibilities of the recording studio, you get the feeling that he is suggesting the prevalence, in mainstream pop, of an unhealthy conservatism. "A lot of artists don't bother to write any material before they get into the studio, simply because there's no point. The music is going to come out of some particular drum sound, or whatever happens on that day or that year is more like it... or that decade is becoming increasingly the case."
Ultimately, Eno remains a cultural champion of subjectivity always preferring the complexities and potential of research and experiment over the dogma of fashionability. Working against the trends of an increasingly formatted and premeditated popular culture, his position is quietly confrontational. "The word I would use to describe the negative effects of contemporary media is 'agendised'. This is a way of asserting control in a free society: you don't tell people what to think, you tell them what to think about and leave every other issue off the agenda, so they don't even consider them." By working to show the social possibilities of music, as allegory, aesthetics and intervention, Eno continues to blur the boundaries between cultural and political space.
Brian Eno and J Peter Schwalm play at the gardens of the Palacio de Cristal, Oporto, Portugal, on Saturday