For those unfamiliar with them, Os Mutantes were a Brazilian psychedelic rock band formed in the late 1960s, combining traditional Brazilian samba styles with electric guitars and rock'n'roll. They were part of the Tropicalía movement, then went vaguely prog before breaking up in the early 1970s. Their music, however, was profoundly influencial on the arty/experimental edge of popular music, influencing the likes of Talking Heads, Stereolab, Beck and Architecture In Helsinki, to name four.
The version of Os Mutantes that played at the Barbican was a reformed one, including some 10 musicians, some of whom looked too young to remember the original band, though was fronted by Sérgio Baptista, the original frontman. They kicked off with a song that was a patchwork of chaos; a few bars in one style, then suddenly shifting to another, and so on, with the musicians changing instruments seamlessly. It worked rather well. The remainder of the songs varied between poignant acoustic melancholia, driving samba rhythm, psychedelic rock-outs and Beatles/Beach Boys-style melodic pop (and often combinations thereof); they did Cantor de Mambo (which they introduced as being about Sérgio Mendes in Los Angeles), starting off as a grooving samba and taking it into full rock mode, El Justiciero (with an introduction lambasting Bush and Blair, to the crowd's applause), Baby (the English-language one), a version of A Minha Menina with English lyrics, and quite a few songs, many of which I didn't recognise. The crowd loved it; first the Brazilians stood up and danced and eventually everybody else joined them. They finished off with a version of Bat Macumba (with Devendra Barnhart joining them on vocals, looking like a cross between a university lecturer and a mediaeval portrait of Jesus) and the crowd singing along (which is not hard), followed by a version of their art-pop/musique-concréte piece Panis Et Circenses, complete with the part where the tape slows to a halt.
The support band was a more recent Brazilian outfit named Nacao Zumbi, who were somewhere between Not Drowning Waving and Faith No More. They had five drummers on stage, with the expected amount of rhythm, a vaguely heavy-rock aesthetic and lilting Brazilian Portuguese vocals over the top. They sounded a bit murky; I'm not sure how much of that was intentional and how much was bad mixing. Anyway, the overall effect was a bit like a heavily armoured post-apocalyptic samba float.
This gig was being filmed as well; there were massive TV-studio-type video cameras positioned all around the auditorium, and as Os Mutantes played, several cameramen scurried around the periphery of the stage, mustering the self-discipline to stand still. I wouldn't be too surprised if this gig came out on DVD at some stage.