What can you reveal about the Christmas Gavin & Stacey?
"It's very much in the style of every other episode of Gavin & Stacey. Their lives are very ordinary and it's a very ordinary Christmas, but it has our usual slant on it. There will be some revelations, but I don't want to give too much away and spoil it. I think people will recognise it as a typical British Christmas with the typical ups and downs people have on that day."
Will we finally found out what went on with Uncle Bryn's "fishing trip"?
"I love it because people make all sorts of things up about it. People say, 'Well it's obviously sexual', but we never ever said it was sexual. People have just decided that it was. All I can say is that it's completely legal in this country and you will find out some more in the Christmas episode."
Are you surprised at the level of the show's success and its promotion to BBC One?
"I am surprised because it gets lots of criticism levelled at it for being too sweet. But I think that's why people are so fond of it, because it's not cynical or edgy. James and I really love the characters and we're so pleased that everybody else shares that. People really think these characters actually exist and genuinely feel like they know them. I meet different people and they all love a different line or a different character. Really random things as well, which me and James often think went under the radar, people tell us that they love."
In one of the trailer clips you make fun of Larry Lamb's new role in EastEnders. Is that going to be a new running gag?
"You have to be careful with intertextual references because it can be seen as a bit of an in-joke, but I think EastEnders is so huge and loved by the nation, so people will enjoy that moment. I know when Larry read that bit of the script he laughed out loud and was really happy to do that."
Do you mind that James is often credited as the show's only creator?
"I know some people think the show is just James's creation, but I don't mind. I did co-write it, but you can't let things like that bother you. You can't control what people say. James and me are very different people at very different stages in our lives. We enjoy different aspects of life. But I would like to see him settle down and have babies. He would be a lovely dad!"
What do you think the chances are that Nessa and Smithy may get together in the show?
"Of course they are not going to get together. People always ask that, but I think it would be totally wrong. But I am proud of the characters we've created and I love the interaction between Nessa and Smithy because it's something different and fresh. I love the bits where they try and greet each other because you wouldn't get a couple more unlikely."
What's the current likelihood of a third series?
"We just have to make sure that whatever episodes we do in the future is as good as what we've done before. We also need to know that the other actors want to do it. It's not just about me and James writing it. Everyone else has to be available. We've never said definitely we won't do a third series, but at the moment we're just enjoying the Christmas special."
Is an American version of the show still in the pipeline?
"There was a script written for NBC. They optioned it, but then that went away. I read the script and it wasn't great to be honest with you. But now ABC are looking into writing a pilot and hopefully that will work out. People claim that we've signed some multi-million deal to sell the show, which is hilarious, because I think we got £2,500 for signing over the rights. We'd only make loads of money if it ran for five series and became syndicated. The only thing that I think has managed that is The Office. Sorry to depress and disappoint, but we're not millionaires yet!
Ruth Jones appears on Richard and Judy's New Position on Friday at 8pm on Watch. The festive Gavin & Stacey airs on Christmas Eve at 10pm on BBC One.