There is a beautiful moment in last year's Call the Midwife Christmas special when Nurse Phyllis Crane presents the contents of the morning's post. Gathering together her team ahead of the day's work, she reveals a Christmas card from Nurse Mount and Nurse Busby and their new puppy Garbo in Scotland – and an aerogram from the late Nurse Barbara's husband Reverend Hereward, safely arrived in New Guinea.


But while it's wonderful to hear updates on our old favourites, the drama doesn't dwell for too long on characters from the past.

Instead, we meet the indefatigable Sister Mildred (Miriam Margolyes), the redoubtable new GP's receptionist Miss Higgins (Georgie Glen), and two soon-to-be midwives, Sister Frances (Ella Broccoleri) and Sister Hilda (Fenella Woolgar). The cast has been replenished, yet again.

Call The Midwife S8 - Christmas Special 2018

So what's the secret behind Call the Midwife's unfailing popularity and its ability to survive those major cast changes?

Partly, it is that the BBC1 period drama has been brilliant at two vital things: keeping the past in the present, and moving ever-onwards into the future. Perhaps that's why it is now in its eighth series and still going strong. Few of our original midwives are still in the picture, but the show survives (and flourishes) even when its biggest stars quit the cast – because no single character is indispensable to the show.

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Now, don't get us wrong: it's not that viewers don't care about the characters.

In fact, fans are often heartbroken when they have to say goodbye. There was genuine grief across the nation as Nurse Barbara Hereward (Charlotte Ritchie) breathed her last (rattling) breath and died of sepsis, and Call the Midwife fans still miss Chummy (Miranda Hart) even though she's been gone since way back in series four.

But the drama's creator and screenwriter Heidi Thomas has been particularly adept at bringing in fresh new talent like Jennifer Kirby (Nurse Valerie Dyer) and Leonie Elliot (Nurse Lucille Anderson) and quickly integrating them into life at Nonnatus House without it ever being jarring.

Nurse Valerie Dyer and Nurse Lucille Anderson in Call the Midwife

The newcomers are gifted with storylines that bring them right into the heart of the story – until you forget that they're newcomers at all. Haven't they always been there?

It is also important that the show's regeneration never happens all at once. Instead, it is a gradual and continual change. Three main characters who appeared in series one episode one are still going strong: Nurse Trixie Franklin (Helen George), Sister Monica Joan (Judy Parfitt) and Sister Julienne (Jenny Agutter) are still central to the show and help preserve that line of continuity.

But when change does happen, Heidi Thomas knows how deeply invested Call the Midwife fans are in each of the characters, and she is mindful and respectful of those relationships regardless of whether they're still on screen or not.

So even as a whole bunch of new characters join the cast, and even as Sister Winifred (Victoria Yeates) leaves Poplar behind, loyal fans will we be glad to spot plenty of framed photos of Barbara around Nonnatus House – and hear all about our old friends and their adventures in Scotland and New Guinea...


Series eight of Call the Midwife airs from Sunday 13th January at 8pm on BBC1

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