PHYLLIS Logan is only minutes back from New York where the actress has been promoting the new Downton Abbey movie. The national station PBS has been beaming out interviews across the nation, given the series about toffs and toff-servers has been such an success in the classless land of the free.

Logan’s voice is soft and a little subdued. She speaks in thumbnails, not given to flourishes at all. I factor in that the expansive, often dramatic language of hyperbole was spoken by very few in Renfrewshire in the 1950s and 1960s, (yet actors tend to be more effusive.) And I factor in jetlag of course.

But then again, perhaps there’s a little more of her laconic head housekeeper character Mrs Hughes in Phyllis Logan than we’d suspected? “Well, I can be a bit snippy, a bit terse,” she offers, smiling. “But only to my nearest and dearest.” Would Kevin agree (actor husband Kevin McNally) agree with that? “Probably,” she says, dryly.

Logan’s thoughts on the Mrs Hughes comparison continues: “She was written down in the script, of course, but I like to think I gave her the legs to run. But when you play a character there are always elements of you in that person. You can’t completely step away from yourself.”

Downton is a phenomenal television success story. The series, which began eight years ago featuring the Crawley family and their legion of servants, began with the Titanic going down, and has covered plague, rape, murder, interwoven with romance, often crossing the class barriers.

Logan’s character was voted No 1 Ever in a 2014 Radio Times poll; no mean feat given the subdued nature of Mrs H, a woman to whom flashes of excitement are to be discouraged as much as relations with those upstairs.

Yet, the original script described Elsie Hughes as a Yorkshire woman. Logan reveals it was only when the casting directors heard the Scot’s natural voice that they asked her to read in her own accent. “I was happy when she was cast as a Scot. She had that Scottish bluntness and I felt right because I have known women like her.”

During the six series of Downton, Mrs Hughes negotiated Branson the chauffeur’s assassination attempt, Carson’s Spanish flu and helped Ethel with her illegitimate Upstairs son, Charlie. The psychologist with an apron also sorted out Thomas’s homosexuality. And although she fell for Mr Carson, (or at least lurched slightly in his direction) it took a bit of persuasion before she agreed to a “full” marriage, where he would make occasional visits downstairs.

“We all know those types,” grins Logan. “But what’s nice about her is she does have a sense of humour. And she’s quite forward thinking. She’s a republican, and has a socialist bent to her for sure.”

Does Logan have left-wing sympathies, considering her late father, an engineer, was a trade unionist? She deflects by referring to Mrs Hughes. “She was of a different type. She knew people were thrown into a caste system but had to make the best of it.”

Yes, but what about you, Phyllis? Did you feel working class containment in Johnstone, where most people’s horizons didn't stretch beyond Rootes car plant or the local carpet factory (where John Byrne took inspiration for The Slab Boys – Logan appeared in the sequel, Cuttin’ A Rug)?

“You just accepted the way things were,” she says, sounding ever so Mrs Hughes. “I never thought I’d break out and become posh. But I did think it would be nice to spread my wings a little.”

Just a little? She smiles and adds: “But I didn’t audition for some of the big London drama schools. I thought that was a step too far for me at the time so I went to Glasgow.”

Not a risk taker. Not a wild child. But very, very good at what she does. Despite her careers teacher declaring the teenager was wasting her time with acting, Logan picked up the James Bridie Gold Medal at the RSAMD. On leaving she landed work at Dundee Rep and worked continuously throughout the 1970s and 1980s with the likes of Borderline Theatre. Real talent was revealed. Yet few would have expected her to land the role of Britain’s most popular posh totty in dodgy antiques dealer series Lovejoy.

Aged 30 in 1986, Logan walked into an audition room as Lady Felsham. Logan’s Lady had a cut-glass accent, spoke authoritatively of renaissance art and invoked a world of stately homes and castles. But in reality, Logan’s only castle connection was her housing scheme, Johnstone Castle, where the recognised art on living room walls was a classic Sara Moon picture. This new cut-glass accent had somehow emerged from a world where ginger bottles were a form of currency.

Logan’s clever deception (aided by being forced to speak RP at drama college) revealed that you don’t have to be a loud extrovert to be emboldened enough to convince you are actually blue blooded: you just need to be talented. “I can’t believe looking back now that 20 million were watching us on Sunday nights. The show was so huge.”

Many other drama successes followed such as Mike Leigh’s Secrets and Lies. But did she feel Downton would be the massive success it became? “I read the scripts and loved them. And when I heard Maggie Smith and Hugh (Bonneville) and Penelope (Wilton) were on board it looked good. Then we signed an option for three series but there was always the chance it could have gone down the pan after one.” Her voice lifts. “And then six came along.”

Did this kill the fear, the insecurity that comes with being an actor waiting to be hired? She answers indirectly. “It used to be that you always knew that when one job was finishing another would be on its way. But that seems to be far less the case these days. That’s why it was great having that guarantee of six months' work each year. And each time it was like going back to school after the summer holidays and seeing your friends.”

Logan seems the worrying type, so why volunteer for a life of insecurity? “And rejection,” she adds in soft voice. “And I’ve had a certain amount of that.” She thinks for a second and makes a dramatic statement that seems out of character. “You know, I wanted this part in Downton so badly I think I might have given up [acting] had I not got it. I don’t often feel that. Usually I have a what’s-for-you-will-not-go-by-you outlook.”

She laughs and allows herself a little flightiness: “Somehow I felt, ‘This is mine! It’s meant to be.'" She then contains herself and becomes more Mrs Hughes. “No, I felt I’d like to give it a bash.”

Logan certainly didn’t get into acting for the glory. She doesn’t seem to be consumed by ambition or the fripperies of acting success. She had genuinely forgotten she’d won a Bridie Gold Medal, and mention of her Bafta for Another Time, Another Place, (the 1983 Scotswoman falls for Italian POW tragic romance) doesn’t swell her head in the slightest. What she does want, however, is to act. All the time. In all the best roles.

“I just wanted to be the best I could. To find the truth in every role. You don’t think about awards. Acting has been the only thing that remotely interested me since I played Mary in the Nativity play at primary school. Then at Johnstone High I’d join every club that had anything to do with acting and take trips to the Citizens'. I’d be in any play going, starting in the chorus and working my way up to playing Polly in the Boyfriend.”

But, of course, there have been set backs. “My dad [David] didn’t live to see me graduate, [he died, aged 59] and that was a real shame but my mum would come and see all my shows.”

Logan’s voice becomes more upbeat as she tells of how her mum and aunt landed roles in one of her films, when the actress appeared in a drama set in Spain, The Legendary Life of Ernest Hemingway (1989). “My mum Betty and my auntie Margaret came on set to have a look around, and they were asked if they wanted to be extras. They loved the idea of this, and were dressed up as posh ladies with big frocks and they had all the make-up done.

“But it was a night shoot, and the second night as they should have been getting picked up they declared, ‘Oh, pet, we don’t think we’ll bother tonight.’ I thought ‘Have you never heard of continuity? Do you know what this means? I had to tell the director they’d both eaten something dodgy.”

Betty and Margaret clearly weren’t captivated by the acting world. Logan herself once claimed she wasn’t captivated by actors. She said she wouldn’t have one in the house, that they were vain people. But then she met McNally while filming the 1993 miniseries Love and Reason and they fell in love and married.

“What I meant was I’d never get together with one,” she backtracks, grinning. “But in a way it makes real sense. We know the business. And we can help each other. Recently, Kevin was doing three episodes of the missing Dad’s Army scripts (playing Captain Mainwaring) and I read lines with him every night. It meant I got to play every other character in the cast.” McNally must have found it a delight, given his wife’s talent. (She slips into a remarkable Clive Dunn/Corporal Jones voice. “Don’t panic, don’t panic Mr Mannering.”

But if all that sounds a little perfunctory, Logan, who lives in west London, once declared: “There’s an excitement in discovering that you can still fall in love when you’re an ancient old trout.”

There’s little doubt the relationship really works. But the Mrs Hughes cross voice emerges when I ask if Pirates of the Caribbean star McNally, who has appeared in Downton in the past, playing Horace Bryant, has a role this time around? “No, he does not,” she says emphatically, (subtext: he’s had his shot and should be thankful, a sentiment which sits neatly against her husband’s quote of the time: “Phyllis said it was like take-your-husband-to-work day.”

Was she a bit territorial? “Yes,” she smiles. “I was thinking: ‘You don’t get me a part as Johnny Depp’s mother and take me to the Caribbean. So why are you here?’”

What of the Downton film, set in 1927, two years after the end of the series? It transpires tiaras and silver will be polished until they sparkle. “We get a visit from the King and Queen (George V and Queen Mary) and there’s a bit of friction between the Downton team and the Royal household staff. Mr Carson (now on gardening duty) is begged by Lady Mary to help out. The cavalry ride into town!”

And, of course, there will be lashings of scandal, romance and intrigue “that will leave the future of Downton hanging in the balance,” says the official movie site.

But what of the future for Phyllis Logan? Despite running up continuous film and TV series, success, from Taggarts to Rab C Nesbitt, from the more recent The Good Karma Hospital to Girlfriends – and attracting great crits for her West End role earlier this year as Patricia Highsmith in Switzerland – she certainly has Elsie Hughes’ worry gene.

Logan’s run, she feels, could end at any minute.

“It’s a snakes and ladders life,” she says in Mrs Hughes' tones. “Your career can be going really well and suddenly the snake appears. But I guess I’ve been lucky because I persevered.”

Nonsense, Phyllis. Talent kicked in. You don’t get Bridies and Baftas and almost continuous work for perseverance. “It’s lovely of you to say so, but I’m not sure that’s really the case.”

Downton Abbey is out on September 13