Last Christmas the midwives were battling heat in a South African mission hospital but December 2017 will be a far colder one for the residents of Nonnatus House.

At least that’s what Call The Midwife's executive producer Pippa Harris hinted at when we caught up with her at the BFI & Radio Times Television Festival.

“There’s come great material coming up,” said Harris of series seven (which will introduce the show's first West Indian midwife) and the upcoming festive offering. “As we move through the sixties each year brings new developments: social developments, medical developments and musical developments!

“Of course, there was the Big Freeze which took place during the period we’ll be covering in the next Christmas Special” Harris teased, “so that’s something to watch out for” 

The Big Freeze occurred during the winter of 1962/3, which was one of the coldest on record in the United Kingdom. There were blizzard-like conditions in the south thanks to heavy snowfall in the latter half of December – and we’re sure that’ll have quite the impact down Poplar way. 

Here’s hoping it won’t cause the midwives too much trouble.

Call The Midwife returns to BBC1 in December 2017