Shirley Henderson isn't famous. Or at least she hopes she isn't. "I don't think I'd be comfortable," says the actor, "if people were spotting me every five seconds. You need to be able to go about your business." Still, with more than 70 roles in TV, theatre, and film to her name, her face – angular, expressive, punctuated by thick, dark eyebrows – will be familiar to many. Children may know her as Moaning Myrtle, the ghost from Harry Potter; others are likely to remember her as helium-voiced Jude in the Bridget Jones movies.
But the majority of Henderson's roles have been in under-the-radar indie films or TV series, with each part quite a transformation: in ITV1's May Contain Nuts – a 2009 comedy drama about pushy parents – she played an 11-year-old girl; then, in last year's Life During Wartime, Todd Solondz's follow-up to his magnificent black comedy Happiness, Henderson was alugubrious Jewish wife.
Such versatility has brought the respect of her peers: Imogen Stubbs and Anne-Marie Duff named her asthefellow actor they most admire, and there are echoes of Tilda Swinton, in Henderson's unconventional choice of roles – and in how sheis becoming the actor of choice for hip, edgy, US indie directors. Yet she can still pass unmolested around her hometown ofDunfermline.
Henderson's latest roles are both in period dramas set in the mid-19th century. In the BBC2 drama The Crimson Petal and the White – an adaptation of the Michel Faber novel also starring Gillian Anderson, Romola Garai and Richard E Grant – she plays Emmeline Fox, a self-appointed rescuer of "fallen women" in a depraved Victorian London. Meanwhile, in Meek's Cutoff, by US director Kelly Reichardt, she is Glory White, one ofa*group of pioneer settlers who get lost in Oregon on their journey west; starving and parched, they end up having to choose between their unreliable guide and a native Americanwho crosses their path.
Neither role is what you might call flattering. Henderson spends most of Meek's Cutoff trudging alongside a cattle-drawn wagon in the burning sun, her features obscured by dirt, sand and an exceedingly oversized bonnet; as Emmeline Fox, she's stiff and palely consumptive, in a high-necked black dress. The same could, in fact, be said of many of her parts: as Moaning Myrtle, she sports schoolgirl bunches and huge, round-framed glasses; in the Bridget Jones films, she is usually swollen-faced in the toilet, crying over some f*ckless boyfriend.
Does she mind never being the . . . "Pretty-pretty one?" She finishes my question. "No. To look good all the time can be challenging. Filming is long – you get very tired, and your skin breaks out and you get lumps and bumps. It's easier if you're allowed to have bags under your eyes."
The Meek's Cutoff shoot was gruelling. Cast and crew spent six weeks in the wilds of Oregon, recreating the arduous journey of the settler convoys. Although the actors slept in a motel rather than under the stars, and were permitted the odd karaoke turn in a local bar, it was a tough experience – but one Henderson would gladly repeat. "We started to respect the journey these people had been on," she says. "They had to get rid of almost everything as they went, for the weight of the wagons. And it's an enormous territory – hard on the feet, hard on the animals. The darkness isdangerous. It will envelop youinasecond."
Henderson has had a number of period roles: she was Morag in the 1995film Rob Roy, and Catherine deBraganza in the BBC's 2003 series Charles II: The Power and the Passion. "I'm always nervous taking on a period role because it's difficult to research – you can't observe it, go out and see it," she says. "But it's satisfying because eventually you think, 'I got there.'"
This work ethic has underpinned Henderson's career: she has a steely determination belied by her diminutive frame, and bolstered by her uncanny ability to play much younger than her real age of 45. She grew up in the Fife village of Kincardine, where she joined an after-school drama group and sang in church choirs, concerts, and during half-time at boxing matches ("Pop stuff," she says, "with an accordion player, and just me tapping my foot to keep time.") A teacher at her college in Fife, where she was studying theatre, suggested she apply to drama school; as her family could only afford to pay for one audition, she took the train to London to try her luck at the Guildhall School of Music and Drama.
"I was determined. One of those people who thinks, 'Ah, that's what Iwant.'" She got in. "I felt very undereducated. I'd never heard of the Royal Shakespeare Company. I didn't know about plays. But I wasn't scared."
Theatre roles in London and Scotland followed, then she moved into TV and film, where she feels most comfortable. "When I'm doing theatre, I feel like my life's on hold. Even though you might go out for a coffee, or go and see a film, your brain is still there, pulling you back to it."
She particularly likes American scripts, she says, because they're often dialogue-heavy. "American scripts are usually non-stop conversation," she says. "People talking over each other. Ilike that. Maybe it's a Scottish thing. The Scots are so bright, clever, have done amazing things in the world. But when you sit there with ordinary Scottish folk, it's just blethers and cupsof tea."
Despite all her successes, Henderson is not so overwhelmed with offers of work that she can't fitin regular shopping trips in Dunfermline. "I'm really not that busy – there's always been gaps. There's probably loads of directors who have no idea what I've done or who I am." She smiles warmly. "And that's fine."
The Crimson Petal and the White is on BBC2 from Wednesday. Meek's Cutoff is out on 15 April.
