Scottish crime novelist Val McDermid has been writing a book a year for the last quarter of a century. Her novels include the series that went on to become the popular TV drama, Wire In The Blood, featuring Detective Inspector Carol Jordan and her sidekick, psychological profiler, Tony Hill.
McDermid has returned to these much-loved characters in her latest book, Retribution. She has sold more than 10 million books to date but she is devoid of the fripperies so often displayed by such successful authors. Her hair is short and grey, her clothes functional and denim; a half-pint of Guinness sits stoutly in front of her.
She says it feels 'kind of weird' having gotten to book number 25.
"I never imagined when I started out that I'd have that many books in me. I'll just keep going until I run out of ideas. PD James is 91 this year and she's writing a book at the moment; she's got deadlines."
Despite her prolific production rate, McDermid says she does not 'churn' books out.
"I've never had the mindset of just doing what can I get away with. For me the ambition is always to make it better or different from what it's been before. Some days you look at it and say, 'that is a pile of shite'. But if you have a pile of shite at least it's something you can work with. If you haven't written anything then there's nothing to polish. That's why, when people ask me have I any advice about writing, I say, 'just do it'."
She admits there is luck and talent involved but for the most part it's just hard slog. "When I wrote my first book I was still a journalist. I was the bureau chief of a Sunday newspaper and that was hard work. I used to write on Monday afternoons, because Sunday papers have Mondays off. That was the time I carved out of my life and I wrote religiously until seven o'clock on Mondays.
"I didn't answer the phone, I didn't answer the door. Everyone thought I was mad. None of my friends or family really believed I'd be published."
Ten million sales later, McDermid has proved them all wrong and still has a passion for writing, although she says it is the characters that keep her interested these days.
'I think it's interesting to write about characters under pressure. It provokes people in ways that are surprising. How often have you said 'that was really out of character' about someone?
"But, when you think about it later, it might be that that was the one incident that has really illuminated who that person is. It seemed to be out of character but actually it was the one thing that told you who they really are.
"Crime readers read a lot and are very sophisticated in their understanding of how the genre works, so there are people who will have figured out where this book is going by page 50, so, for me, it has to be about making the journey interesting for the reader.
"When I started writing Carol and Tony, I intended it to be a standalone novel. So, for me, a lot of the subsequent books has been exploring who they are and what made them that way."
For some readers, they take things to another level by writing their own scenarios for Tony and Carol in their own online 'fan fiction'.
"It's a phenomenon that amazes me. I'm told there is slash fiction out there, too, and I don't even want to think about that.
"Of all my female characters, Carol Jordan is the most straight, she hasn't got a lesbian bone in her body, which is quite heart-breaking really because I find her the most attractive of all my characters."
Retribution progresses Tony and Carol's story further than ever before and for those readers who might be worried about the future, McDermid says there will definitely be another book.
"They have more stories to tell. I have to keep saying to people it's not the end, it's the end of an episode but not the end of the story."
Retribution is published by Little Brown