How James Corden's thirst for fame 'separated' him and Ruth Jones: Candid emails reveal how Gavin and Stacey creators 'broke-up' after he went to LA to pursue celebrity life

Like everybody else, I was enchanted by Gavin And ­Stacey, created by Ruth Jones and James Corden, when it first started in May 2007.

It went on to clock up 22 episodes, including much-anticipated Christmas specials. The final instalment, last December, drew 21 million viewers – figures not seen since the heyday of Morecambe And Wise.

By the time they were shooting the later episodes in south Wales, hundreds flocked to the locations, kept back by security guards. Paparazzi were out in force, pestering the cast. For fear plot elements would be leaked, roads had to be blocked off for filming.

Yet the premise was simplicity itself: fresh-faced Essex boy (Mathew Horne) and lush Barry Island girl (Joanna Page), in the era pre-dating Facebook and social media, get to know each other by speaking on the phone at work. They meet in London and fall instantly in love. Over the various series, they get ­married, buy a house, raise children . . . all very normal and predictable.

Spicing things up were Ruth Jones’s Nessa – allegedly a smuggler and lorry driver, who once went to bed in Las Vegas with two of Gladys Knight’s Pips – and James Corden’s Smithy, Gavin’s ebullient best mate. They made for a gloriously incompatible couple. We kept watching to see whether they’d ­overcome their own considerable quirks.

This book, tailor-made for fans, is a ­transcript (by journalist Boyd Hilton) of a long and ­candid conversation between Jones and Corden, interspersed with coffee-stained ­production memos, drafts, proposal outlines and ­doodles, complete with misspellings and typographical blunders.

Covered in detail is the genesis and evolution of the programme. We also learn much – perhaps too much – about the authors’ ­professional and personal relationship.

Jones and Corden first met on a sitcom called Fat Friends, about a slimming club. ‘I thought you were very nice and sweet, and very young,’ Jones tells Corden. Over drinks at the cast hotel in Leeds, they decided to try writing a show of their own – they had vague ideas about the Welsh encountering the English at a party or wedding reception.

Gradually, it came together, the Shipmans, the Wests, their neighbours the Sutcliffes: all named after serial killers; Billericay versus Barry.

ITV rejected it as too small-scale. They didn’t see it as ‘mainstream’. A commissioning ­editor at the BBC, however, in June 2005, said: ‘I think it could be one of the best things we’ve done.’

Corden, who by now was appearing in The History Boys on Broadway, showed what they’d written to Alan Bennett, who was ‘full of praise for the scripts’. Corden and Jones admit there is indeed a Bennett influence – ‘a lot of that sort of day-to-day stuff. Just not said in a Yorkshire accent’.

Jones, the touch typist, put everything into Word documents. Corden scribbled on Post-it notes. There were lots of laughs, tears, snacks and chocolate. Each ­morning in an office they’d start by saying: ‘Imagine if . . . and then we’d go on a flight of fantasy.’

They frequently met in New York. ‘It was so surreal, writing these scenes set in Barry Island while we were sitting in Central Park.’

The series was given the green light and casting decisions could be made. Rob Brydon was ideal as the pedantic Uncle Bryn. Julia Davis was Dawn the next-door neighbour.

Alison Steadman, as Pam, Gavin’s mother, was sublimely dotty. Having told everyone she’s a vegetarian, she’s then discovered tucking into a packet of ham by Stacey: ‘Promise me thou shalt speak of this to no one !’ ‘But it’s ham, Pam!’

Best of all was Jones’s Nessa, in her black bob wig, heavy eyeliner, and wearing lots of leather – the sort of battleaxe whose locutions are instantly recognisable to those of us who grew up in the south Welsh ­valleys: ‘I’m not being funny, don’t get me wrong, I got to be honest with you, at the end of the day, if truth be told, no word of a lie . . .’ Nessa’s inquiry, ‘What’s occurring?’ became an instant catchphrase.

Jones is in no doubt about what made the programme a hit: ‘It’s about friendship and family and laughter and love, and those are all things that really keep us going.’

As Corden adds: ‘Joy is the ­currency of the show,’ which is true even when there is tension.

Stacey hates married life in Essex and insists on going back to Wales every weekend, even though it’s a long way and the traffic is horrendous; Smithy, who can be sulky and immature, doesn’t like Gavin’s switch from bosom pal to domesticated husband: ‘Your phone’s been off for weeks,’ he complains, when Gavin is on honeymoon.

Everyone has difficulty adjusting. Pam’s ‘little prince’ now belongs elsewhere. And, of course, Nessa gets pregnant.

Audiences were enraptured. ‘It was quite intoxicating, it really was . . . It was life-changing,’ says Corden.

Here the book gets interesting. Corden relished fame, capitalised on it. Jones did not.

‘I think we have experienced fame in different ways, you and me,’ Corden says cautiously. He went to Los Angeles, to be the host of Emmy award-winning talk shows. The Americans adored his bumptiousness. ‘I had some amazing times and great moments,’ he admits.

Jones, more modestly, went back to Cardiff. ‘I just stayed in Wales most of the time and I really did fight against the fame thing.’ She detested red-carpet duties, disliking ­looking dolled-up and overweight in press photographs.

When Corden came to visit her, people excitedly beeped car horns at him – Jones went unrecognised. Corden’s huge celebrity status ‘did sort of ­separate us,’ she says – a point that is rubbed in: ‘I think I found it difficult to deal with that world you were in because I felt it was separating us.’ There must have been a huge financial gulf opening up, too.

Though Jones should be proud of her turn as Hattie Jacques in a biopic and of the 58 episodes of Stella on Sky, it has to be ­conceded that Llanbradach and St ­Mellons, where they made it, isn’t Beverly Hills, where Corden was in his pomp doing Carpool Karaoke with Will Smith and Gwyneth ­Paltrow.

Notwithstanding, the mutual admiration rings somewhat ­hollow: ‘I don’t know if people would ever realise how much you and I ­actually say the words I love you,’ is a typical comment.

‘You walked in, and when I saw you, I just burst into tears. I was so happy to see you,’ Corden remembers about the fact Jones simply attended his birthday party. To which Jones responds: ‘It’s really weird, because I don’t think I always appreciate how much you love me.’ (We must assume none of this is physical – it is all gush.)

More sincere is an email from Corden to Jones in 2015: ‘I feel you’re cross with me or something, or like you don’t count me as a friend any more.’ And here is Jones to Corden in 2017: ‘We’re just in such different places.’ As she adds now in this book: ‘You’d gone into the stratosphere, fame-wise . . . There ends up being a little bit of a disparity.’

They’ve done their level-best to realign. ‘Your performance is one of the greatest of all time,’ Corden tells Jones, which means he thinks Nessa can stand ­comparison with Elizabeth ­Taylor as Cleopatra or Vivien Leigh as Blanche DuBois.

On the final day of shooting last year’s Christmas special, ‘it was probably the most emotional TV or film set I’ve ever been on . . . Everyone was holding each other and singing.’ What an emotionally incontinent lot actors and actresses are.

News recently broke that Corden and Jones are being paid millions to collaborate on a ten-episode series for Apple TV about a local community choir.

Jones is also working with a Stella co-star Steve Speirs on a BBC drama about patients at a knee trauma clinic. Plenty of comedy potential in all these projects.