Keeping up with Ms Jones: From the irrepressible Nessa to warm and witty Stella - actress-writer Ruth Jones is on a roll

Self-effacing and subtle: Ruth Jones (Sky1)

In the first episode of the current series of BBC1's The Voice, Tara Lewis, one of the contestants, announced that she had a new career. Donning a thick black fringe, a stripy top, a leather skirt and waistcoat and a red Welsh dragon tattoo on her shoulder, the 44-year-old from Tonyrefail told viewers that she has recently become a Nessa impersonator. She explained that when she is dressed as the larger-than-life, man-eating character from the well-loved BBC1 sitcom Gavin & Stacey, "I get a great reaction, and I can get away with anything".

To prove the point, Lewis proceeded to ask judge Sir Tom Jones, "What's occurring?" before declaring: "Let's do it, Tom. I'll give you the best night of your life."

The fact that there are now professional Nessa impersonators underscores that, more than four years after the last full series was broadcast, Gavin & Stacey remains an iconic show.

That success has in turn catapulted its two creators and co-stars, Ruth Jones, who played the sublimely self-assured Nessa, and James Corden, who portrayed her lovable on-off partner Smithy, into another league (or A League of Their Own, as Corden's Sky 1 comedy sports quiz would have it).

And even now, eager fans continue to speculate about a comeback for Gavin & Stacey. In an exciting development for the show's legions of supporters, Jones won't rule it out. She reveals that she and Corden often text each other with ideas about where the characters would be now and that they still love making each other laugh.

"James and I have this great chemistry," Jones says. "When we wrote the first Gavin & Stacey script together, we got hysterical. We thought, 'Even if no one else likes it, at least we laughed.' But fortunately other people did like it."

The actress carries on: "Every now and again, James and I say, 'Shall we write another special?'" The difficulty, though, is getting them both in the same room at the same time: "James is majorly busy with a Hollywood film." [Rob Marshall's eagerly awaited big-screen version of the Stephen Sondheim musical, Into the Woods.] But, in another revelation to lift the aficionados' spirits, Jones adds: "The heart is still willing!"

Ruth Jones as the title character in 'Stella' (Sky1)

In the meantime, she has spent the past couple of years creating, writing, producing and starring in Stella, which begins its third, 10-part series on Sky 1 on 24 January. Set in the fictional Welsh Valleys town of Pontyberry, this gentle, good-natured comedy-drama charts the chequered love life of the eponymous fortysomething single mother, played by Jones.

Stella has been another hit for Jones, but what draws viewers to her? You get the impression that they would happily tune in to watch her read out the telephone directory because the actress has that vital likeability factor. Audiences feel that they know her and would love to go for a night out with her.

In person, Jones is as far removed from the character of Nessa as Barry Island is from Billericay. Where Nessa is self-confident and super-assertive, the 47-year-old actress is self-effacing and subtle. Ensconced in a central London hotel suite and wearing an elegant floaty black dress with a rose pattern teamed with smart hooped earrings, Jones uses humour that relies more on the stiletto than the sledgehammer.

At one point, for instance, our conversation strays on to the subject of Rob Brydon, her Gavin & Stacey co-star and old schoolfriend. "Rob doesn't need any more work now he's got an MBE," Jones deadpans. "We can just go around blessing people in a papal way." The joke is made more telling by the fact that Jones herself has recently also been awarded an MBE.

Born in Bridgend, the actress studied drama at Warwick University, where she met Dominic Cooke, who was until last year the artistic director of the Royal Court Theatre in London. She recollects that after graduating she was getting so little acting work, she contemplated retraining as a solicitor. "Thank God I didn't!" she exclaims. "I would've been a disaster as a solicitor."

Instead, she hung on in there in the hope of making it as an actress. But to begin with, it was not easy. Jones remembers "Dominic and I used to be so poor that we didn't even have enough money to get drunk. So we used to sit together nursing one cup of tea for hours in a café off the Strand and say to each other, 'Will we ever be successful?'"

We all know the answer to that. Even so, Jones admits that she has not always found fame easy to deal with. However, one of her New Year's resolutions is not to carp about the attention she attracts. "I decided not to moan any more. Whenever I read an article where I complained about being famous, I'd think, 'Shut up!' I'm a very blessed person. I love my job, and if people want to come up and say hello to me, then I need to be gracious about it."

All the same, she carries on, "When I'm just nipping to Tesco's for a pint of milk in my pyjamas and odd socks and people want my photo, I still think, 'Really? You want a photo of this?' But overall it's a great compliment that people want to come up to me."

Jones with James Corden in 'Gavin & Stacey' (BBC)

Jones's profile has only risen since she started making Stella two years ago. In the third series, the central character is newly single and is studying to be a nurse. She says she has given up on men, but could she be tempted by her attractive new neighbour, a divorced English solicitor named Michael Jackson, who is played by Patrick Baladi from The Office?

Jones, who is married to David Peet, her co-producer on Stella, and has three grown-up stepchildren, reckons that viewers have been enticed by the literally and metaphorically sunny aspect of Pontyberry. "It's no accident that it goes out in January."

They have also warmed to the very likeable title character. "Stella is fallible," Jones muses, "but she is a very good friend. She's very loyal and not in the least judgemental. She's also a really good mother. She's someone you'd want on your side."

Despite the popularity of Stella, Nessa still gets the odd outing. Jones reveals that she recently performed as her vampish alter ego at a charity do in Wales.

She recalls: "As Nessa, I began by telling everyone, 'I've set up home with the Welsh choir Only Men Aloud! – in its entirety.' Then 'Islands in the Stream' started playing, and I said, 'Oh, Only Men Aloud!, what's occurring?' And, one by one, all eight of the choir came on stage."

Jones continues: "At one point, the audience was getting quite noisy, so as Nessa I said to them, 'I'm not getting paid to stand here while you chat.' If your character is rude, you can get away with anything. That's the joy of the character."

The actress closes by reflecting that, "I could have a whole alternative career as Nessa. Generally, I keep her locked up. But everyone has that person inside them who dares to say it as it is. Everyone has a Nessa lurking within them."

'Stella' starts tomorrow at 9pm on Sky 1