Acclaimed American conductor and Bernstein protégée Marin Alsop (b.1956) begins the Bernstein Project tomorrow at the South Bank Centre, a joyous year-long celebration of the legendary composer and conductor Leonard Bernstein (1918-1990). She talks here about her formative friendship with the great man, about their swimming days when he was her teacher at Tanglewood, about his rivalry with Karajan and why she thinks his compositions changed the face of American 20th-century music.