A TV drama about midwives, nuns and moms-to-be set in 1950s London has proved the surprise hit of the season in Blighty.

The first season of “Call the Midwife,” which ended Feb. 19, attracted an average 8.7 million viewers — a 30 audience share — for BBC1, making it the channel’s most popular new drama series in 10 years, and besting the debut season of “Downton Abbey” on ITV.

After two episodes, the BBC commissioned a second season, which will air next year.

The six parter, each episode an hour long, has been described by one reviewer as an “audiovisual cuddle.” But that description fails to do justice to a primetime series showing fairly realistic portrayals of home births — and life in general — in a poverty-stricken district of East London close to the docks.

The show was exec produced by Pippa Harris, who set up shingle Neal Street Prods. with helmer Sam Mendes and producing partner Caro Newling in 2003. Before that, she was head of drama commissioning at the BBC.

The show, based on the memoirs of bestselling author Jennifer Worth, is set in a convent that houses an order of nuns devoted to nursing, and a team of young midwives.

Much of the show’s appeal comes from challenging viewers’ expectations, Harris says.

“One of the pleasures of Jennifer’s writing is that she often turns your assumptions about religion on their head. So you often have scenarios where it is the young midwives who are shocked by people’s morals or their behavior,” she says. “And the nuns — who are far more understanding, because they’ve seen it all before — are unshockable.”

The show comes at a time when the funding of healthcare is a hotly disputed topic in the U.K., but viewers’ reactions to the show on this score can be surprising.

“Just as many people look back with a rose-tinted glow, and think how much more caring the medical profession were then — and just as many people look back and think ‘Gosh, what a terrible time to have given birth,’ ” Harris says.

The series was penned by “Cranford” and “Upstairs Downstairs” scribe Heidi Thomas and helmed by Philippa Lowthorpe, and benefited from the cross-pollination of the different talents among Neal Street’s partners. “As a company, we work in feature films, TV and theater, and the three of us — myself, Sam Mendes and Caro Newling — we’ve always worked (on) each other’s projects,” Harris says. “Sam was around to look at the early cuts of those first episodes, and I think Philippa found his notes some of the most helpful in terms of shaping the finished episodes.”

This is the company’s first drama series, following a string of feature films, including “Revolutionary Road,” “Away We Go” and “Jarhead.” It has a first-look deal with Focus Features, for which it is developing “Middlemarch” and “Butcher’s Crossing,” and is developing a feature film version of TV series “Lost in Austen” for Sony.

Further TV series are in the works, including a U.S. remake of French cop series “Spiral” for L.A.-based BBC Worldwide Prods., being penned by Meredith Stiehm (“Homeland”); and Paris-set hostage thriller “Grand Hotel” for Canal Plus. Both are being developed with French company Son et Lumiere.