At the beginning of last season the National Theatre’s Nicholas Hytner lowered ticket prices in an attempt to draw younger audiences. It worked. “It represents a triumph for Nicholas Hytner, the National’s artistic director, who gambled on filling the giant Olivier auditorium with audiences for edgier plays, if ticket prices could be reduced. Two-thirds of the thousands who flocked to see the musical skit based on the American television show were under 35, and they all came at full price. Nearly half had never been to the National before. “