This year, in the BBC Symphony Orchestra's January Composer weekend, it is the turn of the often controversial Scottish composer James MacMillan to come under the spotlight, in a series of concerts entitled Darkness into Light. Ever since his visceral orchestral showpiece The Confession of Isobel Gowdie - aobut an innocent Scotswoman denounced, tortured and murdered as a witch - aroused a near-hysterical reaction at the BBC Proms in 1990, MacMillan has become known for his ability to strike emotional chords.
The BBC's festival takes its name from his symphony Vigil, which marks the transition from darkness to light at the heart of Easter. Roman Catholic, socialist and Scottish issues burn fiercely in MacMillan's music, as do the themes of birth, life, death and renewal.
He appears mild-mannered, even laid-back. But he has made no secret of his often controversial political, religious and national concerns. His vehement attack on sectarianism in Scotland, made during the 1999 Edinburgh Festival, in which he likened anti-Catholicism in Scotland to Northern Ireland "without the guns", shocked the arts world, the Church and the Scottish establishment. He attracted more headlines when he accompanied the premiere of his Second Symphony with the claim that Scotland was a cultural desert.
The son of a joiner and a teacher, he was born in the Ayrshire mining village of Kilwinning, and brought up in nearby Cumnock. Piano and trumpet lessons sparked an interest in music and, at the age of 12, after hearing Alexander Gibson conduct Scottish Opera in Wagner's Götterdämmerung, he was in no doubt: he wanted to compose.
"There were tunes in my head that had to come out," he recalls. And the physical experience of music moved him, he adds: "the shock of Stravinsky's The Rite of Spring or the experience of Debussy's La Mer seeping up through the soles of my feet. But Palestrina, Victoria and Bach remain the most important composers of the past for me."
His manner may be earnest, his demeanour rather formal and his left-leaning, liberationist roots in the Roman Catholic faith a little daunting, but in his youth MacMillan did gigs, playing penny-whistle and keyboards in crowd-pleasing Scottish and Irish folk bands, as well as singing ballads. He's steeped in traditional Scottish culture and also enjoys rock music for its exuberance and directness, even if he finds it tame compared to the world of contemporary classical music he now inhabits.
Early milestones such as the music-theatre piece Busqueda, incorporating poems by the Mothers of the Disappeared in Argentina, or Tuireadh, for clarinet and strings, commemorating the Piper Alpha oil-rig disaster, reflect the intensity of his response to contemporary events. But would he agree that he is gradually adopting a more universalist outlook? "I can detect a deeper reflection, stemming perhaps from a keener interest in reading philosophy, theology, poetry and a host of writers. I'm fascinated by what other artists do, by the wider world beyond my particular art form and by its potential to impact on music and to shape thoughts."
MacMillan describes his music as having a potential for drama. "I take my music to extremes and let it do battle. We live in an age of continual daily contradictions, so it makes sense that music should deal with conflict. But there's something about being an artist which needs to make sense out of chaos - like moulding clay."
Darkness into Light: The Music of James MacMillan: Barbican; St Giles, Cripplegate; and Guildhall School Music Hall (0845 120 7550; www.barbican.org.uk) 14 to 16 January