Two years ago, Daniel Jackson was an unknown when it came to playwriting. Some knew him as a press officer at Glasgow's Tron and Citizens' theatres and as the writer of a comic strip in the List magazine, but as a dramatist his credits went no further than a couple of lunchtime shorts in the Play, a Pie and a Pint season.
There was certainly no guarantee of success when Ayrshire's Borderline theatre announced it was going to produce The Wall.
As Jackson remembers it, the fact that his father, Eddie, just happens to be the linchpin of Borderline only made the risks seem greater. "My dad was taking an awful risk by taking it on, because I was his son," he says. "Also, every other theatre in Scotland had turned that play down. It was a real leap into the unknown and it could have killed both of our careers stone dead if it had gone badly."
Happily, it turned out to be a risk worth taking. The Wall, a very funny comedy about Stewarton teenagers, was rapturously welcomed.
In the 2008 Critics' Awards for Theatre in Scotland, Sally Reid was nominated for best female performance, Jackson was nominated for best new play and the company picked up the award for best ensemble. Suddenly, it no longer seemed fanciful for Jackson to imagine there could be a follow-up.
In 2009, he caught up with the same characters two years on in The Ducky, offering more rites-of-passage hilarity. And now, just a month after the opening of Jackson's Edinburgh Fringe First-winning hit, My Romantic History, he is completing the trilogy with The Chooky Brae.
"I wrote The Wall through a Playwrights' Studio Scotland scheme and I can remember vividly telling my mentor, John Tiffany, that it was a trilogy and him pooh-poohing me in the strongest possible terms," he says. "He was right to do so, because you have to be insane to think, writing one play, that there's any chance you'll get to do the other two parts."
This time, we have moved forward another two years to a Christmas Day in Stewarton where Norma, whom we first met as a gauche 14-year-old in The Wall, has just had a baby, while her mother is trying to cope with her ex-husband having a stroke and her son having a breakdown. "I really liked the Norma character as I was writing the first one and I always thought it'd be good to see what happens to this little girl," says Jackson, who created the part with Sally Reid in mind and is delighted the actor has been able to perform the role in all three plays. "I've always thought Sally was the best actor of her generation. She's spectacularly talented."
Like the first two parts of the trilogy, The Chooky Brae - which takes its name from a real hill in Stewarton where the teenage Jackson would hang out - is an unashamed comedy, this one being the most frivolous of the three, although not without its moments of poignancy. The playwright is a devout believer in popular theatre and the art of giving an audience a good time.
"I wanted it to be like the sort of movies you sit and watch with your family at Christmas," he says. "Because I was fortunate enough to go to the theatre a lot when I was a child, I was exposed to it and I understood the power of live theatre. But if I hadn't had that experience, would I have been exposed to it? I do feel theatre practitioners are becoming more navel-gazey and increasingly putting on plays for their pals. I'm not anti-intellectual - I like that stuff too - but it's got to be a pyramid and, in order to support that kind of work, there's got to be a larger base that introduces people to going to the theatre. There is less and less popular work being made in Scotland, so the kind I do is important for everyone."
Next on his plate is an episode of River City, a two-minute micro-play for A Play, a Pie and Pint, commissions for the Royal Court and the National Theatre of Scotland, and a piece for Random Accomplice written with fellow Ayrshire writers Douglas Maxwell and Johnny McKnight.
While he keeps an eye on feedback from the post-Edinburgh tour of My Romantic History in Birmingham, Sheffield and London, he will be watching the launch of The Chooky Brae with a mix of pride at having achieved so much in two years and regret at saying goodbye to his favourite characters. "I always had in mind that it would be a trilogy but it's taken me by surprise that we've been able to do it and in such rapid succession."
• The Chooky Brae is at the Tron, Glasgow, until Saturday, then on tour until 2 October.