Wynton Marsalis is pictured  mastering a questions and answers session at the Barbican in London. Unusually, I didn’t have a pen to take notes. And nobody around me had one either. Pens are becoming extinct and people have given up writing things down. Is shorthand a dying art?  Marsalis is engaging, intelligent and articulate: every question was met with a profusion of enlightenment. The questions came thick and fast from adults and kids, but mostly kids. All the questions were smart and about jazz. He likened improvisation to natural and effusive speech, that it must be in essence individual, as original as a fingerprint, or DNA.  Jazz, basically, has its own grammar, where some choices turn out to be better than others. What is the sweetest tune Marsalis has ever played? To date, Danny Boy. He was asked to play it at the funeral of a musician.