Call the Midwife is Sharrock’s second television project after her much-praised film of Henry V for BBC Two’s The Hollow Crown sequence of history plays last year. She faced a similar problem with that but running helped her there, especially when it came to her time-pressured lead actor Tom Hiddleston. “I was opening a show at the National [Theatre] just before we started and Tom had just come back from America. He came to my press night but as I never watch them I went for a run. So he ran with me and we ran up and down the Thames on the South Bank and I made him do all those huge speeches to the elements while we were running.”