The next series of Call the Midwife will feature the show’s first health visitor and first use of a ventouse during a birth.
Set in 1968, it will also be heavily influenced by Enoch Powell’s divisive anti-immigration speech - which saw him ejected from the shadow cabinet.
Show boss Heidi Thomas explained: “The first episode of the new series coincides with Enoch Powell’s famous speech about rivers of blood, which did change the way people of different cultures and ethnicities act with one another, and we felt we couldn’t ignore that.”
On the show’s new arrival - not yet cast - she explained: “We do have a new nun joining us, Sister Veronica, who arrives in the first episode.
"Sister Veronica is going to be our very first health visitor, she’ll be helping us steer through the policies that were new at the time - she’s very involved in what we call preventative health, for example nutrition and supporting families.”
Thomas said that “vacuum extraction” will be demonstrated for the first time - with an episode in which the team are sent on a training course.
She added: “Whether Doctor Turner can afford to buy a ventouse machine is another matter. It might be like the incubator and need fund-raising.”
The Christmas special will bring a return of actress Liz White as Rhoda Mullucks, whose daughter Susan was a victim of the thalidomide scandal.
Thomas said: “We meet Susan again at the age of six coming to terms with artificial limbs. We see the impact that has on her parents.
"They’re right at the heart of everything because their story enables us to do what we’re good at - it’s about humanity, endurance and what love can do.”
She said that the drama’s 12th run would also depict the growing gulf between rich and poor in the late 60s.
“There’s no way you can deny our series will echo something we’re seeing today and that’s quite harrowing, to think 50 years down the line, some people are still having the same problems as their parents and grandparents had.”
