The "Call The Midwife" Christmas special will be set during Britain's coldest winter.
The show's writer Heidi Thomas has revealed the upcoming festive special of the popular BBC One programme will be set during the cold snap of December 1962, where up to 20 foot of snow fell and lakes and rivers started to freeze over.
Heidi told TV Times magazine: "This was the coldest British winter for 300 years, with persistent blizzards, gales and two solid months of vicious icy conditions.
"It was a legendary winter and will provide us with an amazing background for our Christmas visit to Nonnatus House."
Meanwhile, Heidi previously revealed "Call the Midwife" will be introducing its first West Indian midwife as a regular character this year.
Of new character Lucille, she said: "We'll be introducing our first West Indian young regular midwife to Nonnatus House in series seven. She's going to bring stories with her and a different cultural point of view and that's very exciting.
"My research is continually bringing up new things. One thing we're really looking forward to in series seven is my research has made me very aware of the contributions made by West Indian and Caribbean nurses to the NHS in the early 1960s.
"Elegant, funny and clever, Lucille is swift to settle in and bring a fresh new energy to life at Nonnatus House. Casting is currently underway and we look forward to introducing Lucille to our 10 million fans very soon."
Heidi's new idea came just a few days after Ben Caplan announced he would be stepping down as PC Peter Noakes.
He said: "I'm taking a break to concentrate on other things. Much as I love playing Peter Noakes, it's great to go off and play some more edgy characters and show a little bit more diversity."