*Warning: Contains spoilers* The Christmas special of Call the Midwife is the first without Jessica Reine and it isn't diminished for her absence. Jenny Lee may have been the locus point of the action, but Call the Midwife has always been an ensemble piece. Jenny is still there in one form, with Vanessa Redgrave as the narrator who now receives a bit of screentime as she considers writing her memoirs. The books that the television series is based upon are a good deal darker, nastier and more sinister than what we get on screen but you can still count on Call the Midwife for a bit of seasonal misery. This year, the theme is archaic and inhumane institutions of the early 20th century. Very festive. And so we are reminded that the poor are always with us at Christmas. This year's paupers in question are the always excellent Kacey Ainsworth and her lover. They are both former inmates of a lunatic asylum and they live a life of desperate poverty. Thankfully for them, a nurse has come along to patronise them and feel sad on their behalf. You can't eat moral platitudes, Cynthia, but thanks for that. The second storyline concerns a home for errant girls, where young women in the family way used to go to discreetly give birth and pass their children on for adoption without arousing the sneers of the neighbours. This home is run by a bad woman. We know she's bad because she immediately declares herself to be a stickler for hygiene and that's a clear insanity signifier. As it progresses, she reveals herself to be cruel, imcompetent and a gin-soaked lush. Thankfully, all it takes is a bit of sass from one of the pregnant girls and she's away with the wind and the girls from Nonnatus House are on their way to provide maternal care, morally dubious emotional blackmail and lashings of ginger beer. Call the Midwife is essentially an exercise in nostalgia for a time that never existed except perhaps in Ann Widdecombe's wet dreams. The good and the bad are easily distinguished, and all it takes to vanquish evil is a jolly good ticking off, poverty is a tolerable inconvenience and sometimes even a blessing, love is pure and forever and every woman is a perfect mother in waiting. Or a nun. Yes, it's sentimental, mawkish and morally vacuous at its worst but it's almost impossible to dislike. There is no malice or cruelty and it has a heart which makes it more than bearable. Besides, it's an impressive feat to make blood, guts, gore, destitution, and unyielding human misery into something so sweet and wholesome. Call The Midwife is on at 7.50pm on BBC1 on Christmas Day.