Popular period medical drama Call The Midwife has received a fifth season order as filming on its fourth season wraps. The BBC One series, which airs on PBS in the U.S., is produced by Sam Mendes’ Neal Street Productions and has been one of the most-watched dramas in Britain with all three runs to date averaging over 10M viewers per episode (delayed viewing included). The season 3 UK premiere last January was the highest-rated ever of the show’s career, with a 36.1% share in the overnights. Season four kicks off in the UK with a Christmas special next month followed by the regular series in January.

Heidi Thomas created the drama that centers on a group of nurse midwives working in the East End of London beginning in the 1950s. Miranda Hart, who won the Best Actress prize at the National Television Awards last year, stars. (She’s also in Paul Feig’s upcoming comedy feature, Spy, with Melissa McCarthy, Rose Byrne, Jude Law and Jason Statham.) Joining the regular cast for Season 4 are Linda Bassett (East Is East, Lark Rise To Candleford) and Charlotte Ritchie (Life Of Riley, Fresh Meat). Vanessa Redgrave will be seen during the Christmas special as Jennifer Worth, the nurse upon whose eponymous memoirs Call The Midwife was originally based.

The fifth season of Call The Midwife will consist of a Christmas special in 2015, followed by eight hourlong episodes in 2016, bringing the action into 1961. There are no U.S. dates as yet for Season 4 or 5, although Season 3 began airing this past March on PBS.

Thomas continues to lead the writing team with Pippa Harris as executive producer for Neal Street. Executive producer for the BBC is Christopher Aird with Annie Tricklebank returning as producer.