Claire Foy never saw Sugapuff coming.  How could she have? The British actress — who won an Emmy for her brilliantly contained and internal portrayal of young Queen Elizabeth II sublimating her every desire and dream for her duty in The Crown Season 2 — was finishing up the Q&A after her late Thursday keynote talk at  SXSW London when an ebullient man in the audience cried out for the microphone. “I’m here!”  Foy, who’d been a delightful sport all night, brimming with laughter and self-deprecating British humor, gestured for the usher bearing the mic to hand it over.  “Yeah?” she asked, smiling expectantly. “Claire Foy, it’s so beautiful to see your natural self and not acting,” said the man, who I’d later learn is Sugapuff, a pop culture presenter from East London.…