Specializing in contemporary music that frequently incorporates experimental methods such as open instrumentation, London's Plus-Minus Ensemble—commonly shortened to Plus-Minus—has mounted an extensive series of premieres for new works. Composers Joanna Bailie and Matthew Shlomowitz established the group in 2003, and the two perform on whichever instruments a given program requires. The remaining members comprise pianist and accordionist Mark Knoop, who also conducts, clarinetist Vicky Wright, pianist and Messiaen specialist Roderick Chadwick, electric guitarist Tom Pauwels, violinist Marcus Barcham-Stevens, and cellist Alex Waterman.
The ensemble takes its name from Karlheinz Stockhausen's 1963 composition of the same title, a piece whose open instrumentation permits realization by any combination of instruments and ensemble sizes. Plus-Minus has made such flexible scores a specialty, presenting not only the Stockhausen work but also Louis Andriessen's Workers Union (1975, "for any loud sounding group of instruments") and Cornelius Cardew's Treatise. Premieres by the group encompass pieces from Øyvind Torvund, Erik Ulman, and Lawrence Crane, alongside other conceptually driven compositions and works involving electroacoustic resources.
European contemporary-music series that have featured Plus-Minus include Open Ear on BBC Radio 3, Barcelona's Sampler Sèries festival, and Copenhagen's Klang Festival; the ensemble's 2019-2020 schedule further encompassed the Warsaw Autumn festival. In 2019 the organization adopted a collective management structure, with Knoop and Wright joining Bailie and Shlomowitz as co-directors. Workshops have been led by the group at multiple British institutions as well as at Stanford University in California, and in 2019 Plus-Minus was appointed Ensemble-in-Residence at the Reid School of Music at the University of Edinburgh. The same year saw the release of the ensemble's debut album on the NMC label, which presented Bailie's Artificial Environments scored for field recordings, vocal narrator, and chamber ensemble.
