Danny Boyle is the Academy Award-winning British director who's given us Trainspotting (1 and 2), Sunshine, 28 Days Later, The Beach and now Yesterday, a film all about a big 'What if...?' What if one day, only one person in the world remembered The Beatles? Ali talks to Danny about how this Richard Curtis-written comedy came about, shooting sci-fi and what mementos he's taken back home.