SHE'S famous for playing powerhouses of dissatisfaction, inscrutability or downright treachery, yet offscreen January Jones is closer to a romantic-comedy heroine.
She's self-deprecating, even a little goofy: when she was invited to a Playboy Halloween party, most of the women dressed only in bodypaint. Jones, on the other hand, came gloved-up and powdered as Michael Jackson.
Cast as the chief villainess in the new movie X-Men: First Class, she talks up her character's brain-bending telepathic battles as "James McAvoy and me spending a lot of time staring at each other".
Even her name, which could pass as a nod to her wintry screen roles, gets defused.
"It's a stripper name," she pans. It's also her real name, taken from an airport novel, "Everyone thinks it isn't but my dad named me after a character in a book my mom was reading. He thought January sounded cool and he takes 100 per cent credit for my success because of the name."
The name may not be classic but her look has been compared to Grace Kelly at the time she was Hitchcock's favourite blonde. Jones has heard this so many times she can practically finish the question.
"I take it as a compliment of sorts because I'm a fan of all those movies. Grace Kelly, Tippi Hedren and those kinds of women were blonde and beautiful and had a very interesting, mysterious quality about them. But I struggle with the comparisons a little bit because I have a lot more fun and I don't want to have to be something that I'm not."
You can see her point. Jones is more like Kelly with the froideur wiped off, especially as she starts to relax and open up a little.
Just five years ago, Jones, 33 was a relative unknown. At 18, she opted for a modelling career over a college degree, against the advice of her parents, a high school teacher and a sports shop manageress, and flew to New York from South Dakota on the second plane of her life.
"When you're young, you run towards the fire, you feel no fear," she says.
"I couldn't do it now." She met the son of a billionaire investment banker and started dating, and found jobs with Clearasil and Abercrombie & Fitch, but while New York smoothed away her small town accent and manners, she quickly grew bored with modelling and relocated to Los Angeles, hoping to land some acting parts.
Her 1999 screen debut was "Number One" in a TV movie called Sorority and "Girl" in The Glass House.
She played a lesbian porn star in the Jack Nicholson comedy Anger Management, then one of the hot American girls who drape themselves over Kris Marshall in Love Actually, horrifying the film's producers on her first day when she informed Richard Curtis that her character's lines didn't sound authentically American.
Apparently charmed by her chutzpah, he cast her again in his next picture, The Boat That Rocked, which she didn't enjoy so much because her scenes were on the pirate radio boat "and I got so queasy".
Jones is naturally funny, but onscreen it's something that only Curtis has seized on. However, she shyly admits she used to hang out with the Judd Apatow comedy crowd, working on a show called North Hollywood, which failed to take off.
By the mid-2000s, her biggest role was in The Three Burials Of Melquiades Estrada, which was nominated for the Palme d'Or at Cannes, and American Pie: The Wedding, which was not.
Three Burials was directed by Tommy Lee Jones, who is no relation although it didn't stop one journalist asking what it was like being directed by her father.
But it was her Betty Draper role in Mad Men, with Jon Hamm as her first husband Don Draper, that truly changed things in 2007.
In a well-dressed drama set in the 1960s, brittle, unhappy, chilly Betty has become an icon of oppressed domesticity. Yet when Jones first signed up, it was by no means certain that the character would make it to the first episode.
She had auditioned for the role of Peggy, struggling copywriter in a man's world. Mad Men's creator Matthew Weiner thought Elizabeth Moss was a better fit, but offered Jones the role of Betty.
At that stage, the character was an afterthought, a piece of background for Don Draper with just two lines in the pilot. "I definitely thought of it as a consolation prize," admits Jones. Weiner promised the role would grow, and overnight wrote two "Betty" scenes.
In fact, Mad Men is chiefly notable for its women – the career-girl, a foxy office flirt, but above all, frustrated 1960s housewife Betty, who believes in family, probity and white picket fence happiness but gradually, cruelly, has it all taken away from her.
Motherhood is unfulfilling (the Mad Men crew once put together a blooper reel for Jones which consisted solely of scenes where Betty screams at her kids).
Marital relations are so arctic that she sits on the washing machine during the spin cycle and fantasises about salesmen. When she discovers her husband has been having affairs, it's the fact that everyone knew bar her that forces her to divorce. A mental breakdown is telegraphed by Betty wandering around in a cocktail dress for two days.
"People come up to me and say, 'Poor Betty' and I have to convince them I'm a very happy person with a nice life," laughs Jones.
"In a sense, I don't understand Betty because if something isn't going my way or I feel trapped in a situation I will get out. It's hard for me to understand how she can put on a smile and be the happy housewife."
The show's portrait of pre-equality sexism might seem remote to Jones, who wasn't born when the first equal rights legislation was put into place, but she notes that 50 years on from Mad Men's period setting, we haven't left double standards behind; after putting up with Don Draper's constant philandering, Betty finally sleeps with someone outside the marital bed. Shortly after the episode aired, Jones met Senator John McCain. As soon he saw her, he pulled a face of mock horror.
"He said, 'Oh how could you!' I said, 'You're weird, John McCain, and I am not Betty.'"
Female fans, however, have been more supportive: "They loved that she took a stand at last. They were like, 'Yes!'"
Inevitably Jones' own relationships have been scrutinised for signs of Betty-style frustrations. After first meeting on Abercrombie & Fitch assignments, she started dating Ashton Kutcher in 1998 while trying to break into acting. In these pre-Demi years, Kutcher was not very supportive, telling her: "I don't think you're going to be good at this."
"I should thank him," retorts Jones. "If you tell me I can't do something, that makes me more motivated."
She was also in relationships with Jim Carrey, musician Josh Groban, and more recently comedy actor Jason Sudeikis, a fixture on the US TV satirical sketch show Saturday Night Live.
The two began dating last summer, when Sudeikis was freshly divorced from his wife of six years but Jones says the long-distance affair eventually overwhelmed them: Sudeikis lives in New York, Jones is based in LA. In January – the irony – they announced they were still friends but called it quits.
Then earlier this month, once all of the X-Men interviews had been done and dusted, her publicist announced she was looking forward to a new chapter of her life as a single mother, while declining to name the father. Sudeikis has also curled away from the discussion. Asked for a comment, he replied: "I'd rather – yes but no."
Due to give birth in the autumn, Jones has made no secret of her longing for a family.
"Why do this if there's no-one to share it with?" On the other hand, she admits she is strong-willed and while that has helped her career: "I've probably been unattractive to some men because I say what I feel and what I think."
She certainly seems a lot more secure about herself than most actresses, so it's paradoxical that the success of Mad Men, which has brought her Emmy and Golden Globe nominations, has also brought her scripts for "other sad housewives".
"I say no to all the sad roles I'm offered. I'm sad for five months out of the year when I'm playing Betty. I don't really want to be sad at any other time."
Earlier this year she was cast as Liam Neeson's wife in Unknown: not sad, but like Betty, a sexy enigma. No wonder she jumped at the chance to play a mutant with mental powers, diamond-hard skin and an all-white wardrobe, Emma Frost.
"I had auditioned for both Emma Frost and Moira in LA. There was a month or two of shooting left on Mad Men and the movie wasn't supposed to start while we were still shooting.
"My impression was it wasn't going to work out, schedule-wise but then it got pushed so I was happily able to do it. The day after I wrapped Mad Men, I flew to London. There was no break. I went from being a 1960s housewife to a mutant."
Living in the UK for four months of filming gave her a fresh appreciation for certain British mainstays – namely our sense of humour, Topshop clothes and Wagamama noodles. She also immersed herself in everything X-Men. "My big question was: why are they so angry? The comics really helped.
"But if anyone has our outtakes, I hope they put them out because they are quite special. At least James can pull his special Charles Xavier pose, but when we're playing our telepathy mind games, really it's just us staring at each other for a really long time."
The first thing that strikes you about X-Men: First Class is that the prequel to the three previous X-Men films is set in the Kennedy era.
"Yes, I only do projects that take place in the 1960s and that have 'Men' in the title." cracks Jones.
"But it doesn't feel like a period movie, and it's been really cool to go from something that's very wordy and emotionally taxing to something where there's a lot of action sequences and I get to wear crazy outfits and fight and be telepathic. It's been a really lovely change of pace. It's all of this crazy stuff where you're looking at a tennis ball and using your imagination. It's like going to work like you're a four-year-old and having a lot of fun with it, playing mental mind games with James McAvoy."
During filming, it was rumoured that Jones had gone on a strict juice fast in anticipation of the barely-there outfits. Not so, says the woman who also claims to be allergic to workout regimes.
"I went from Mad Men, where we're encouraged not to work out, to the next day where I was this really ripped, hot mutant. How's that going to happen? Am I going to do ab crunches on the plane?"
Instead she did weights and tried to strike flattering poses. "You just need to walk on to set with confidence," she says easily. "I'm a petite person so I didn't want to go on a strict workout and eating regime. But I have been working out with a trainer and boxing – I get really bored with exercise, so if it's something that I can do that's fun, that's great.
"I've got a Nintendo Wii and I've been doing some Wii fencing. Not sure how much that helps, but I do work up a sweat in here occasionally, with fencing or tennis. Whatever helps."
Despite the revealing clothes, Jones plays Emma Frost with the same opaque sensuality that has made mad men of us all. But it's also re-ignited the debate of Can January Jones Really Act? Or is she an actress with a shtick that you can slot in whenever a stunning ornament is required? Jones tends to choose unreadable characters, and that mystique has sometimes been read as blankness.
She's much more vivid offscreen, and perhaps her next film, a thriller called The Hungry Rabbit Jumps, where she plays Nicolas Cage's wife, will allow her to kick against an image that has served her well so far, but cries out for some diversity.
There's no denying, however, that Jones ticks all the boxes for X-Men. In the movie, as in the comics, the first thing you notice about Emma Frost is not her mind, but a remarkable body with gravity-defying clothes.
It's not the only clothes horse role she's had lately – she is a face for Versace and was recently featured in a string of promotions that seemed to require little more than vertiginous heels, a lot of flesh and a thoughtfully-positioned handbag – but there's a moment where Jones brings the role of X-Men's ice queen some heat: a scene where she seems to have got through to her longtime companion Sebastian Shaw (Kevin Bacon) – only to be treated like a cocktail waitress in the next instant.
As Frost chips off a lump of ice from an iceberg into a glass of whisky, Jones is quietly affecting for a supervillain.
Who knows – maybe in the next film, she may be allowed to melt a little bit more.
X-Men: First Class is on general release from Wednesday
This article was first published in Scotland On Sunday, 29 May, 2011