It would not be festival time at Edinburgh without the sound of bagpipes on arrival at Waverley station, a centuries-old welcome to the Scottish capital. In recent decades, though, classical music in the city and beyond has gained its own significant Scottish voice. James MacMillan, born in Ayrshire in 1959, first came to notice around 1990, and through a combination of flair and hard work (Macmillan diligently keeps up a stream of new pieces) has become one of the leading composers of his generation.