IT’S possible that all you need to know about Ruth Jones you can learn from the story she tells about the time she went to James Corden’s wedding. She brings it up while defining the difference between herself and her Gavin & Stacey co-creator.

“He knows who famous people are,” she is telling me as you join us. “At James’s wedding this guy sang a song at the end as part of the service. I thought: ‘That’s lovely. That might be someone James worked with at Bella Pasta back in the day.’”

Jones then met the singer afterwards. “We were all chatting and he came up and I said: ‘It’s lovely, that song you did. It was really nice.’ He said: ‘Oh, thanks very much.’

“And I said; ‘So, where do you know James from?’ And he said: ‘Well, we met when he came and sang with us at one of our concerts.’

“And I thought: ‘Oh, shit, I’ve got this all wrong.’ I found out afterwards it was the lead singer of Snow Patrol.

“So, I’m really not good in that world. I just get it wrong, so it’s better for me to stay out of it. It’s kind of why I live in Cardiff. I’m not going to find any paps [paparazzi] at the end of my drive.”

And that’s why James Corden is a Hollywood face, an American TV chat show host and pops up in those Confused.com ads on your telly every night, while Ruth Jones doesn’t … Mostly.

And yet. And yet. The truth is Ruth Jones might not be sitting in cars doing Carpool Karaoke with Ed Sheeran or Will Smith, but she is herself part of “that world”. She is both the co-creator and star of Gavin and Stacey, and still gets recognised as Nessa from the show even though the last episode aired in 2010.

READ MORE: Nerina Pallot on her "death and shagging" album

She is also the star of the Welsh comedy drama Stella, which she co-created with her TV producer husband David Peet. Not bad for someone who says she has been dealing with self-doubt since her teenage years.

And if that was not enough she now has to add another hyphen to her name badge. “Ruth Jones, author.”

This month sees the publication of her debut, Never Greener. It is a romantic comedy that contains love and desire, a largely Scottish setting (Edinburgh and Portobello loom large; turns out Ruth Jones loves Scotland), enthusiastic cover quotes from Jojo Moyes (one of Jones’s favourite writers) and Jane Fallon and something of a new start for her.

Ruth Jones, author. How does that sound? “So exciting. We did this thing with Transworld in November which was sort of a pre-launch evening with five debut novelists and I had to wear a little badge that said: ‘Ruth Jones: Author’. I said to my editor: ‘I love that. I absolutely love that.’ Then she had a proper little name-plate made up for me with it. I’ve got that on my writing desk.”

Today is the last day of February and even as we speak the Beast from the East is roaring. Outside the London offices of Jones’s publishers snow is swirling and my phone has already pinged to tell me my flight back to Scotland has been cancelled. In the end it will take me four days to get home.

But, right now, that’s ahead of me and, flight worries aside, I’m enjoying myself in Jones’s company, listening to her stories about her new career and the one we know her for best.

Rather like her TV shows, Jones in person is all warmth and approachability. And yet now and again you see these glimpses of insecurity that are hard to square with someone who has had two hit TV series, a number one hit (with Rob Bryden and some bloke called Tom Jones) on a cover version of Islands in the Stream for Comic Relief) and a two-book contract.

Never Greener started as a screenplay 15 years ago. “I think one production company optioned it for six months, but nothing came of it and I kind of forgot about it.”

Then, two years ago, on a spa break she was glancing through old files on her laptop and she came across it again, thought there might be something in it and decided to have another pass at it there and then.

“I would go off for a massage and I couldn’t wait to come back to keep going.”

She wrote 10,000 words, got in touch with a literary agent (and not just any agent but uberagent Johnny Geller; they were at uni together) and next thing she knew publishers were in a bidding war for the rights to it.

In Never Greener, Callum, a married man, restarts an affair after a 17-year gap with Kate, now 39, who in the years between their flings has become a TV star.

The story was inspired by Friends Reunited, she says. “Do you remember that? There were all these stories of people who had contacted old lovers, their first love from school thinking: ‘Oh yeah, that’s the person I should have been with.’

“And I just thought it would be quite interesting to reignite a flame that had gone out. What would it be like? Are we the same person 17 years later? Because I think – and I’ve found this from reading diaries from when I was 13 – there are certain elements where you almost don’t recognise the person [you were]. You go: ‘Was that really me that thought like that?’

“And then there were other things that remained constant. I would say for me elements of self-doubt that I had when I was 13 I still have at nearly 52.”

It’s a book that contrasts love as passion and love as companionship, you might say. I’m presuming Ruth you recognise both. “Yeah, everything changes as you get older. I’d like to think I’ve been a passionate individual in my time.”

Well, yes. So maybe this is a good time to talk about sex. Because if nothing else Never Greener is a great endorsement of middle-aged canoodling, I tell her. “Oh, thank you.”

It’s a tricky thing to write sex scenes, Jones says. “When you see something graphic it just jumps out at you. Even if you write the word ‘nipple’ … There are just certain words that are going to make you laugh,” she says.

And, yes, she is laughing as she says it.

“You probably can’t write this in The Herald, but my friend said to me: ‘Oh, God, you haven’t any cocks in there, do you? Or any hardness or any mounds?”

There are, you will be pleased to learn, none of the above in Never Greener.

“I keep imagining my mother reading it … But then my mum’s great. She always says: ‘I don’t mind the sex, it’s the swearing I don’t like. She hasn’t read it yet. She won’t like the swearing.”

There’s a line in the book where her character Kate talks of the “annoying neediness and ego of all the actors she’d been involved with.” Ruth, are you giving us the inside gen here?

No, she says. “I can remember certain actors saying: ‘Oh, don’t marry an actor. Two actors together you’ve got two egos. But, I mean, clearly that’s not true. There are a lot of successful marriages between actors.

“I think, by virtue of the fact that you’re a performer, you’re going to be insecure and insecurities need to be reassured.

“I’m sure I’m bloody needy as well. I can probably be a right actress at times. In the acknowledgements I’ve apologised to my brothers and sisters and said: ‘Thank you for putting up with your drama queen of a sister.’”

Every actor I meet tells me they’re insecure, though. And yet you all present as confident, outgoing people.

“I think you can certainly hide behind a character. Someone was asking me about Nessa. She’s very different to me as a person, but I love playing her. If I do a charity event as Nessa I love it because I can be really rude.

“I don’t know why we get insecure. I suppose because you rely upon people telling you how good you are or whether you pulled it off. If someone says: ‘I saw you in the TV play the other night. You were absolutely dreadful.’ You think: ‘Well, possibly a million people have seen that and thought that I was dreadful.’”

You haven’t had that, surely? “Well, no. But this is why I don’t go on social media, because I couldn’t bear it.”

When I ask Ruth Jones to tell me a story about her childhood she starts talking about her father Richard, who was a legal executive for British Steel. He died last summer and inevitably she has been thinking about him.

“You reach these milestones in your life and you start to reassess your life or you become aware of your own mortality. Somebody who had been in my life for 51 years was gone. But what was great was at his funeral me and my sister and my brothers were able to talk about stories about growing up. We all did a eulogy at the service. Memories of dad.

“We grew up in Porthcawl in south Wales and in the summer holidays after work mum and dad would take us to the beach after six o’clock at night when it was still hot. My brother said: ‘My abiding memory of dad will always be him getting us to run into the sea and him running in with us, the waves bouncing up against his chest, and him doing a Tarzan yell.’

“And I thought: ‘Oh, God, I’d forgot he used to do that.’

“He was such a personality. And very, very Welsh.”

Her eulogy contained a story her friend Cerys had told her. It could easily be an out-take from Gavin and Stacey.

“He’d been in hospital a couple of years ago and he was like a dad to her and she took him a banana which she’d bought at the hospital.”

Jones accentuates her Welsh accent at this point to tell the story.

“Richard, I’ve bought you a banana.”

“How much you pay for it?”

“65p.”

“Take it away. I can get 10 for a pound in Lidl.”

She smiles at the memory. “He loved getting a bargain.”

Her parents brought up four children. Jones was the third to come along. Her brothers and sister still live in Porthcawl. Jones drama studied at Warwick University and after graduating joined a touring company set up by Dominic Cooke, who went on to a starry theatrical career at the Royal Court and the Royal National Theatre.

Jones thought her career was set. “And then the work didn’t happen, and I found myself getting a temp job working for Kensington and Chelsea Borough Council, applying for jobs from the back of the Stage newspaper and not getting anywhere.

“I thought: ‘This is ridiculous. I’m going to give up.’ So, I decided to move back to Cardiff and become a solicitor. The most hilarious thing ever.”

She was saved from this fate by the Teenage Mutant Ninja Turtles. Or at least a part as one in her local panto. Which Ninja Turtle did she play? “Michelangelo.”

Even back then her parents had a sense of what she might be capable of. “Mum and dad felt for me, because obviously it wasn’t happening. My mum used to say to me about writing. I did have this annoying thing where I felt not good enough. I do look back and think: ‘Oh, why did you waste your time thinking like that.’”

In the end she did finally seize the means of production after a chain of connections. She was spotted in the film East is East by the writer Kay Mellor who cast her in TV show Fat Friends, which, of course, is where she met James Corden. And during their downtime from filming they sat in the Crown Plaza Hotel in Leeds where they came up with the idea for Gavin & Stacey.

When Gavin & Stacey started to become huge how did she handle the attention? “I think I probably handled it well for what suited my personality. I often say James and I went to the Baftas, the show got two Baftas and I went down the M4 and James went stratospheric.

“But he is good at being in the public eye and he embraces it, enjoys it. It’s part of his personality."

In the wake of Gavin & Stacey’s success and the subsequent backlash against James Corden (how dare he become a success and enjoy it, seems to be the takeaway line), Gavin and Stacey is seen as a little uncool these days. But it’s still my favourite sitcom of the 21st century.

Partly because it appeared at a time when I didn’t think I’d laugh again (serious illness, deaths in the family, lots of crappy life stuff) and partly because its vision of working-class life was warm and inclusive and frankly that felt like a statement at the time. It still does. As its commissioner, the then BBC Three boss Stuart Murphy said, it’s characters “weren’t being sneered at.”

When I bring up the C word, Jones rather dances around it. She’s not sure what class means now, she says. But then she starts talking about Stella and the people she met in the Welsh valleys where they filmed it.

“Belinda, whose house it was which we used to film, said: ‘Oh yeah. Everyone knows everything that goes on.’ And I love that. I love the fact that still happens. You hear all the time ‘community’s broken down.’ I’m not sure.

“There’s such shit going on. It’s so ….” She whispers the swear word “… f****** awful, the stories you read. But there is still plenty of good in people. Look at the reaction when Grenfell happened, or when the Manchester bombing happened – taxi drivers taking people home. There is still good in the world and that’s what I like seeing.”

And there in a nutshell is the secret to Ruth Jones’s success. She sees the good in flawed people and puts it on the screen. And, now, on the page.

Is she ambitious? A little. Talking of her love of box sets (she’s rewatching Borgen at the moment) she says that she actually got in touch with the casting director of The Crown – another of her favourites – about the chance of playing the older Princess Margaret. “She didn’t reply and then I found out Helena Bonham Carter was doing it.”

For years she would say she wanted to make a film, write a play, maybe a book. Now she’s done the latter.

But then, she says, ambition changes, doesn’t it? “My ambition now is to remain healthy and when that day comes when I shuffle off that mortal coil I want it to be sudden. I don’t want to linger.”

“I want my family to be happy and I want contentment and I would quite like the world to calm the f*** down. That would be really nice, wouldn’t it?

It would indeed. Outside,the snow keeps falling.

Never Greener, by Ruth Jones, is published by Bantam Press, priced £12.99.

The Herald:

Ruth Jones and family at Stirling Castle

RUTH JONES ON HER LOVE OF SCOTLAND

“I’m a big Scotlandophile. I love Scotland. I have been going there on and off for different things for years. I’ve been up there for the rugby. I’ve been up for the Edinburgh festival, but also up to Sutherland, up to the north-west coast, to the Orkneys. It’s the most stunning place.

“We did have fantastic holidays in Scotland. I have this picture of us in Stirling. Is there a memorial to Robert the Bruce? All six of us standing in front of this. I’m the little girl in the pink dress at the front standing in front of my brother Julian, next to my other brother Mark, my sister Maria in the pushchair, dad Richard and mum Hannah.

“We must have caught some Highland games too and there’s a picture of me trying to do the Scottish dancing. God, I was precocious even back then.”