Call the Midwife creator Heidi Thomas has written countless emotional storylines across the show’s 15 seasons, but the confirmation that Sister Monica Joan is nearing the end could well be the most devastating. It was confirmed in the most recent episode that she has chronic kidney disease, for which there is no cure. “Unless we can persuade her to accept what treatment there is, she’ll progress to end-stage renal failure fairly quickly,” warned Dr Turner (Stephen McGann), as a sombre Nurse Crane (Linda Bassett) vowed to “love her as we always have, but a bit more carefully”. Actor Judy Parfitt – who is now 90 herself – has been part of the beloved period drama from the very beginning, bringing a singular wit and gravitas to the role, and becoming a firm favourite among much of the viewership – all of which makes imagining the show without her a near-total impossibility. Thomas told Radio Times that while it was “hard” writing the season 15 finale, it was also “beautiful”. “Many of the things that I …