Was Celia the one who was supposed to get hit by a car driven by Agent Gough? Wasn't it implied that she died after being hit by the MI6 lady, with the MI6 lady getting the call Gough was supposed to get?
She got a call to tell her Celia was in hospital and not doing well, but not the one on April 29th to say she was dead - she said during that phone call "you're going to call me again on April 29th"...