British drama Call the Midwife returns to BBC First on January 19 with the horrors of THALIDOMIDE casting a long shadow over the series.

Set in London of the early 60s, the series about the nuns and nurses of Nonnatus House is now in its 5th season with Charlotte Ritchie back as young nurse Barbara Gilbert.

"It's definitely as good as the series can be and introduces more elements of that changing period of time that they're living in.  We're getting new storylines that deal with the beginning of the whole Thalidomide problem.  It was such a powerful period and I think it’s really important that this story is told to a younger generation and also remembered by the people who lived it".

"There's a lot of drama and conflict in this series.  The trials and tribulations, as well as some really wonderful stuff for the girls.  It's very much 'old versus new' which creates a lot of interesting conflict and Barbara is at the centre of some of it".

Ritchie joined the series at the beginning of season four, filling the gap left by Jessica Raine who played midwife Jenny Lee.  She admits to being a fan of the show before joining the cast; an experience she found just a little daunting.

"I'd watched the show a lot with my mum and I joined when it was already a success.  I came into it as a fan, so I wasn't surprised by its popularity.

But then it kind of hit me one day that I was surrounded by these amazing women.  And these characters are so defined.  They're not the same type of people having the same type of conversations. They're all very resolutely 'their own people' who have endless, interesting and relevant stories that are base on real stories". 

Call The Midwife has built a huge following outside of the United Kingdom, prompting the BBC to commission a sixth season before the premiere of series five.

"It's so nice too because you don't get that tentative feeling at the end of the season, waiting to know if you'll get to do it all again.  I was thinking while we were filming this series 'would there be another one? What's going to happen?" It's such a joy and a relief to know that I get a whole another summer doing it.

"It's amazing that it has such longevity.  It's in its fifth series, going into its sixth and there are so many stories to explore".

Season 5 of Call The Midwife premiers on BBC First, Tuesday January 19 at 8.30pm