Gavin & Stacey star was working in a shoe shop and all set to quit acting for good.

Actress Joanna Page was working in a shoe shop in south London, knee deep in a massive box of crocs, looking for a size 12 pair, when the call came through from her agent about Gavin & Stacey.

“I was ready to jack it all in, I hadn’t had any acting work for about a year and the auditions were drying up,” she admits. “And I actually liked working in the shoe shop. Getting dressed in nice little outfits in the morning, going off to work with my packed lunch, meeting my friends after work for a drink. I was happy being around normal people, not actors, who can be a***holes.”

Climbing out the box and racing to the phone, the much-loved Welsh star describes in her debut memoir, Lush! My Story – From Swansea to Stacey and Everything in Between, the moment that changed her life forever. She writes: “My agent said, ‘A TV script has just landed on my desk and I think you’ll like it. It’s a sitcom about a Welsh girl and an Essex boy who fall in love and it is very funny.’“I hesitated. A sitcom? But I was a serious actress wasn’t I? Wait a minute? Did you say Welsh girl?

Jo felt she was in the last chance saloon as far as her acting career was going. But having worked in mainly costume dramas at the National Theatre and for the RSC for years, she just didn’t see herself as a TV comedy actress. “I wanted to be the next Kate Winslet,” she laughs but when she read Ruth Jones and James Corden’s script, aged 29 she quickly realised, “I am Stacey”.

Still, she was over the moon. “For the first time in my life here was a role that felt authentic and real to me,” she says. “It was my life, my world, my family and everything I knew. Right down to the fact my actual mum makes omelettes all the time, like Gwen in the show. “And when I moved to London to go to RADA, my Uncle Anthony gave me a rape alarm just like Uncle Bryn gives Stacey when she goes to London to meet Gavin for the first time.”

Jo’s whole future as an actress was riding on the audition. In the book she writes: “I’ve got to get this part. In fact if I don’t get this part because some f***** who’s got famous parents gets it or some celebrity whose not even an actress gets it then that’s it, I’m done. This is my last shot.” But despite not being able to do the Cardiff accent required for the role, the 29-year-old from Swansea nailed the rest of the audition and got the part. What followed was 20 years in one of Britain’s best loved sitcoms across three award-winning series and three Christmas specials. The final episode last December was watched by a staggering 12 million viewers.

But while Joanna has finally stopped being Stacey on screen, the similarities between her and character – hugely family orientated, funny, warm, honest, dramatic – are still there. The only difference is that in real life she is a mum of four to Eva, 12, Kit, 10, Boe, 8 and Noah, 3, while Stacey has three children.

And naturally for a cast of people who gelled so brilliantly on screen, her TV family are all still in touch. “We all support each other and go and see each other's plays and meet up for coffee whenever we can,” she says.

“I love them all so much. We have a Whatsapp group called ‘Christmas is Occurring’ where Rob Brydon posts pictures of where he is in the world and we have to guess.”Jo describes in the book how she spent much of that final day on set with Ruth, James, Rob, Alison Steadman, Larry Lamb and her TV mum Melanie Walters in tears at the thought of saying goodbye.

But today she says: “I’ve drawn a line under that part of my life now. I was 29 when I became Stacey and I am 48 now and a mother of four. And I want to be at home with my kids, picking them up from school, making their tea. I fancy writing children’s books maybe. I tell them enough stories at bedtime. I could take myself off with the dogs to our caravan in West Wittering and write. That’s what Ruth does. She just goes to a cottage in Scotland and writes.”

Jo is married to former Emmerdale actor James Thornton, 49. They both appeared in the 1999 TV serial David Copperfield (Page as Dora Spenlow and Thornton as Ham Peggotty) and were married for ten years before she focused on becoming a mum aged 35.

James has also scaled back on his acting work to help raise their family. He now does voiceover work from a studio he built in the garage at their home, Lavender Cottage, in the Oxfordshire countryside. It all sounds rather, well, lush. But life wasn’t always so rosy for Jo.

After “a very happy childhood” growing up in Swansea and being part of the National Youth Theatre of Wales she got a place at RADA (the Royal Academy of Dramatic Art) in London. Funding was an issue so her mum wrote begging letters to whoever she could think of including Sir Anthony Hopkins who contributed generously.

“My mum was so supportive. It was before the internet but she took herself down to the library and spent hours doing research and writing letters.” But the experience turned into one of the most miserable times of Joanna’s life.

“I arrived so open and optimistic and passionate and it was absolutely brutal,” she remembers. “Every day I was told by a teacher I was s**t, that I couldn’t act, I was too pure, too pretty, too short, too Welsh, an ice queen. I thought maybe they were breaking me down to build me up but they didn’t do that. It was brutal."

Jo found comfort in her friend Maxine Peake who was “very working class and very sure of who she was” but admits she spent a lot of time “crying in the toilet”. Maxine would look after Jo’s hamster Tarzan when she went back to Wales most weekends and the pair remain good friends.

Jo says: “I know other actresses like Daisy May Cooper and Phoebe Waller-Bridge have spoken about their awful time at RADA so I know now it wasn’t me. I couldn’t understand why they had offered me a place if they thought I was so bad. It has made me incredibly thick-skinned but it was a brutal experience.”

Her book details another low career moment when she unsuccessfully auditioned for the part of Baby in Dirty Dancing. “I’d practically been brought up on Dirty Dancing and was told I would be perfect for the role,” she recalls.Needless to say, after a hilariously bad audition she didn’t get the part.

“I walked out the theatre thinking, ‘Don’t cry, don’t cry’ and then I got out into the Strand and I burst into tears,” she writes. “I was in such a state. I was crying and covered in chocolate and had just started my period and I was broken. Then I saw the Savoy. I thought, I can’t go home after that, so I went in and booked a room.

“I was sobbing on the floor of my hotel room in the robe working my way through the mini-bar, the champagne, the Pringles, everything. Then there was a knock at the door and someone from the hotel had a little tray with some chocolates on it for me because they had seen how upset I was.”

The book is packed with similar anecdotes of her successes, and frank and funny failures. She tells tales of her dad and James Corden falling drunk into hedges after glamorous award ceremonies and there is plenty of blood and gore when it comes to her four complicated births.

“All of a sudden at 35 I woke up one morning and was feeling unbelievably broody and I said right that’s it I want a baby” she writes. “I’d never pictured myself having children. I was an actress.”From the woman who played Just Judy in the 2003 rom-com Love Actually in which she is completely naked in several scenes, it is not surprising to discover that Jo is certainly no prude when it comes to revealing personal details about her life.

However after four children she has no intention of doing nude scenes in the future and her dream role now would be to play Miss Marple. I love Agatha Christie and would love to play her in a quaint English village.”

In the meantime she has presenting stints on ITV’s Loose Women and BBC2’s Joanna Page’s Wild Life, where she trains to become a wildlife rescue volunteer.

“TV presenting fits round my family but when the kids need me less I definitely want to go back to acting...and writing,” she says. She is aware though that it all could have turned out very differently and she remains the family loving home body.She writes: “There’s a side of me that would have liked to have stayed in Swansea. I would have lived down the road from my mum and dad, worked in the local shop, married a local lad from Swansea and had kids straight away.

“I’ve missed a lot of family life, weddings, funerals and parties and the day to day but that’s what you do when you become an actor.”

* Lush! My Story – from Swansea to Stacey and Everything in Between by Joanna Page published (Sphere, £25) available from the 25th September available in hardback, eBook and audio