'There must be some way that we can advance trans rights without attacking women's rights.' He said: 'She's been demonised as some kind of witch who wants to destroy trans people but she just wants women's spaces to be protected. The Trainspotting/Porno/Dead Men's trilogy has its harrowing moments but overall these books are mainly fun to write.The 64-year-old Scot said the Harry Potter author was simply 'trying to protect women's spaces' It's hard to have that voice in your head. The books that are most difficult to write have been Marabou Stork Nightmare and Filth, where the main character is despicable and does terrible things. What’s the emotional / psychological impact on you of writing a ‘Trainspotting’ book versus another book? There's nothing you can do to improve old books once they're out there, so it's pointless wasting time thinking about them. Most writers will say the same: you are totally engrossed on the project you are currently working on. The only time I go back to them is if I'm working on a TV or film adaptation or on a sequel/prequel. I tend not to think about any of the books I've written. In comparison to all the other books you’ve written, do you think of ‘Trainspotting’ differently? How or why?

With a new set of characters you spend a lot of time working out exactly who they are. You stick them in a room together and they'll tell the story for you. It's easier to write a book with established characters. How do you approach these books versus your others, not involving these characters? You’ve written other books about Renton, Begbie, and the gang. Irvine Welsh (Photo by Ulf Andersen/Getty Images) Ulf Andersen/Getty Images I think it's a book about the redundancy of humanity in a post-industrial age, but you could argue all serious literature has to be concerned with that big theme now. What do you make of this characterisation? It's been called the book of a generation. It's a selfish act – I write the books I want to read. Who did you intend the book for, or who did you think would be its greatest fans? You want to entertain, but I'm primarily a confrontational writer – I like to challenge, not just reinforce my own certainties of the world. The problem is getting genuinely relevant ones and telling them well. If you're a proper writer you will never run out of stories to tell. The Acid House was finished around the same time as Trainspotting. I was writing a lot of stuff at the time. Was ’Trainspotting’ the only story you could imagine writing at the time? Or were there other stories that you dabbled in / wrote around the same time that were never finished or published? Photo by Liam Longman Liam Longman/Figment/Noel Gay/Kobal/Shutterstock/Liam Longman/Figment/Noel Gay/Kobal/Shutterstock

Trainspotting by Irvine Welsh