Johnston studied for both a degree in music and a master"s degree in Music and Media Technology at Trinity College Dublin (Bachelor of Music 1982) and has a Doctor of Philosophy in composition from the National University of Ireland, Maynooth. Initially he had also studied at the Royal Irish Academy of Music, Dublin (flute with Doris Keogh, clarinet with Tim Hanafin, and composition with James Wilson). He completed his education with the English composer Robert Hanson.
In 1985 he was invited by European Community Youth Orchestra to write an orchestral piece under the guidance of György Ligeti. 1989-1991 he was Chairman of the Association of Irish Composers. Johnston"s output includes works for both orchestra and smaller ensembles, some works of which include electronics, and two operas.
His music has been performed at many venues and festivals including the 1985 Asolo Musica Festival in Italy, the 1996 International Society for Contemporary Music Festival (ISCM), the 2001 Sonorities Festival of Contemporary Music in Belfast, and Radio Teilifís Éireann"s 2005 Living Music Festival.
His use of system is unusual among Irish composers, his compositional process typically including a significant element of pre-planning. 1989 – Macaulay Fellowship, Arts Council of Ireland.
Aosdána]
1996-2001 - Appointed as member of the Board of Directors of the National Concert Hall of Ireland, An Ceoláras Náisiúnta.
