The BBC has announced plans to make a Call the Midwife film and prequel TV series set during the Second World War.

It comes as filming begins for the 15th series of the BBC One drama, which follows a group of nurse midwives working in London’s East End from the late 1950s to the start of the 1970s.

The film will be set in an as-yet undisclosed overseas location in 1972, and will feature characters from the existing TV show.

Meanwhile, the separate prequel series will “delve into the deeper past”, showrunner Heidi Thomas said, offering a view of life in Poplar, east London, during the Blitz.

The new, separate film and prequel projects will be written, created and produced by Thomas and executive producers Dame Pippa Harris and Ann Tricklebank, who will also oversee the production of series 16 of the programme together.

The prequel series will feature “some familiar (if much younger) faces”, Thomas said.

She said that while she has “never run out of stories for our midwives”, she had found herself “yearning to delve into the deeper past” than the years 1957 to 1971 which have been covered by the show.

“The Blitz years in the East End were extraordinary – filled with loss, togetherness, courage and joy,” she said.

Meanwhile, the film will see the “much-loved” regular characters “take a short break from Poplar and test themselves in an unfamiliar landscape”, Ms Thomas said.

The location of the film remains “top secret”, she added – but said it would look “absolutely fantastic” on the big screen.

The first series of the show was originally inspired by the memoirs of Jennifer Worth, who worked as a midwife and nurse in the community in Poplar.

Dame Pippa said the prequel series and film project were being made partly for a “new, younger generation who have also fallen in love with our characters and the challenges they face.”

The 15th series will begin with a two-part Christmas special which will see characters travelling to Hong Kong on a mercy mission.