By 1975, when they headed a jazz quartet together at a Swiss jazz festival, saxophonist John Tchicai and pianist Irene Schweizer were, if not legends, then certainly heavyweights in the free jazz world. The Copenhagen-born Tchicai was most renowned for playing alto sax on John Coltrane's monumental 1965 Ascension recording; he had also recorded with Albert Ayler and collaborated with saxophonist Archie Shepp and cornetist Don Cherry in The New York Contemporary Five. Swiss pianist Schweizer had worked with numerous free jazz luminaries across Europe during the late '60s and early '70s, including German bassist Peter Kowald and English saxophonist Evan Parker.
In the mid-'70s the two musicians headed a quartet which also included German bassist Buschi Niebergall and South African drummer Makaya Ntshoko. The group performed in August of 1975 at the first Willisau Jazz Festival in Switzerland. It was an inspired and emotional bit of group improvisation, marked by Tchicai's moody, ethereal, endlessly meandering alto and soprano sax parts and Schweizer's eerie piano tinkling. In 1976, an extremely limited recording of the performance, entitled Willi the Pig, was issued in a batch of 500, making it one of the rarest of all free jazz albums. When asked which of her out-of-print recordings she'd most like to see reissued, Schweizer said Willi the Pig, and so, accordingly, John Corbett and the good folks at Atavistic reissued the long-lost album.