Jessica Raine may have locked up her bicycle and folded away her nurse's uniform, but it seems the Call the Midwife star can't escape the 1950s. She's back on the BBC this summer in Partners in Crime, a six-part adaptation of Agatha Christie's Tommy and Tuppence spy novels. The Beeb is hoping the slightly hapless husband-and-wife crime-fighting team will prove as popular as Poirot or Miss Marple.
Raine plays Tuppence; David Walliams, Tommy. The series moves the action along a little from Christie's originals: the alliterative couple have settled into a comfy, bickering marriage, which gets a dash of spice when they unwittingly find themselves spying on a network of seedy Soho criminals. "I get to be this incredibly curious, slightly frustrated housewife – and go on all these escapades, and dress up, and be a spy!" Raine beams at the memory.
The 32-year-old is best known as the prim Jenny Lee from three series of the phenomenally popular Call the Midwife, which she has now left. She's grateful for her casting, but while she doesn't spell it out, I suspect she (like some viewers) found Jenny a bit of a drip. Other recent roles have included Jules Sutter, the beleaguered wife of a former military man, in the psychological thriller Fortitude, and Jane Rochford, sister-in-law of Henry VIII, in Wolf Hall. "They were [also] both very put-upon women. I was really keen to do some comedy, to lighten up a bit," she says. "Tuppence is quite confident – and just fun!"
What about stepping back into another period drama – was she nervous about getting stuck in the 1950s? "The way I negotiated it with myself was that I couldn't not do it because it was the 1950s. We had a wonderful costume designer – the same as from Call the Midwife – and she was determined to make me look different."
Part of that physical transformation was lopping off her dark curls. "Initially, I did look like Dudley Moore. A week of trauma, and then we got filming, and they styled it beautifully."
Tommy and Tuppence are as ripe for reinvention as Raine's hairdo. A previous version of Partners in Crime aired in the 1980s, starring Francesca Annis, but for many viewers, this will be the first time they see the duo. The new series is directed by Edward Hall, better known for his work as artistic director of the Hampstead Theatre, and, as Raine explains, "He did all six episodes, which is very unusual in television. It made a real difference – he knew exactly where the characters had come from. He bowled me over with his vision."
How did she find working with Walliams? "I was obviously aware of who he is but, I don't think we'd met. He has a flamboyant side, but from the first reading, he underplayed it, which allowed Tuppence's role to be a bit bigger."
Decent parts for women is a serious topic for Raine – as it is for many actresses now willing to speak out about the feeble characterisation or inequality of opportunity in the industry. "I had a period of turning things down," she says. "It's amazing the number of poorly written women out there." She's quietly optimistic, however, that the situation is improving. "There are a lot of cool women putting up the magnifying glass [to their faces]: 'I'm judged by this; what are you men judged on?' I'm not moaning – I've played some great women – but the situation needs to keep changing."
Raine jokes that she's now "post-ingénue", but acknowledges that, for the acting game, she started relatively late: she graduated from Rada at 22, having been to university. She was blessed to have "a bit of babyface", meaning her early roles in the theatre were often stroppy teenagers – including a memorable turn in Mike Bartlett's Earthquakes in London, in which she first met her partner, fellow actor Tom Goodman-Hill.
Raine is desperate to get back to the theatre: "I do love a bloody big stage!" Indeed, it was being taken to the West End as a child that made her want to be an actress: "That amazing feeling when the curtain opens: 'Oh! There's another world – on the stage!' I remember very early on having strong feelings about what I liked or disliked. I went to see Les Mis and absolutely hated it. I was just like: 'I hate all the urchins!'" Here she cackles wickedly, before gulping: "Oh my god, it's still on, terrible thing to say…"
But while her heart may be wrapped in red velvet curtains, it was being on the box that really made her career. With Call the Midwife, she was suddenly being recognised on the street and popping up in the tabloids. "I don't think you ever get used to it. And that was so overnight: it's a quite unique experience."
Even if you're not a Midwife fan, chances are you've seen Raine's pixie-featured face in something, whether being killed off in Line of Duty, bossing it as TV producer Verity Lambert in An Adventure in Space and Time – a dramatisation of the conception and early years of Doctor Who – or scheming as Jane in Wolf Hall.
She particularly adored the latter series, saying it is an excellent argument against the current Tory attack on the BBC. "It was a perfect piece of television; the scripts were flawless." She also relished her small, but vicious, part. "My inner bitch was satisfied," she laughs.
That inner bitch – not terribly visible in the enthusiastic, empathetic woman before me – might also rear up in the project Raine is currently filming: Jericho, for ITV, in which she plays a tough Yorkshirewoman in a drama about the building of the viaducts during the Industrial Revolution. "These shanty towns popped up – lawless, as there's no infrastructure. There's this carnival atmosphere, but terrible things happen… And she's not an RP character! She's a proper northern woman, really tough and dry."
If you assumed Raine was part of the coterie of posh British actresses taught Received Pronunciation in the cradle, you'd be wrong. She grew up on the Welsh-English borders, on a farm half-an-hour from Hereford, and considers herself a "border girl". "I find it quite difficult to say where I'm from because no one knows where it is, and I've got a funny accent," she says. "But actually it does inform your identity: I'm neither one thing nor the other; I can shift quite easily."
Not that she pines for the countryside – she lives with Goodman-Hill in London, and has embraced city life. "The countryside is so beautiful and I love going back – but I am a complete Londoner now. And I never thought I'd say that! I love the culture: going to the theatre, films, galleries. I just want to suck it all up."
What did her parents make of her fleeing for the bright lights? "They knew early on that I wasn't really a farmer," she says archly. "They were probably quite shocked that I wanted to be an actress – they supported me, but they were just worried. I'd be worried if I had a daughter who said she wanted to be an actress."
It's a surprising statement, perhaps, from this polished pro – because if there's one woman who makes a career on stage and screen look as easy as riding a bike, it's Jessica Raine.
'Partners in Crime' will air on BBC1 this month