I also needed a destination where people stay long enough for the first part of the plot to work itself out.

Shops, tearooms, dances and, most important of all, potential suitors. In the original, Bath is the destination for all things desirable. Having created this small universe for Cat, the next thing I had to figure out was where it would collide with the wider world. But from my experience of teenagers, it's clear that a substantial tranche of them don't explore much beyond the immediate circle of their friends. Yes, that still leaves the internet with all its gateways on the world. Add to that the social politics of a mother trained as a teacher who doesn't want her brood exposed to the horrors of the local school system and insists on home schooling. So, no money to spare for exotic foreign holidays or even extensive travel in the UK. Cat is one of four children of a Church of England vicar. What I came up with was a background closed in on itself by a mixture of social politics and poverty. How could I create a credible 17-year-old with that degree of naivete in 2014? She has no weaponry to defend herself against the sophisticated wiles of the people she encounters and her very innocence is the crux on which much of the plot turns. Unworldly, inexperienced and guileless, she is catapulted into society when she's taken on a trip to Bath by her wealthy neighbours, the Allens. Austen's Catherine Morland is an innocent abroad. Nobody does that better than Austen, and nowhere does she give it greater rein than in Northanger Abbey.

But I've always loved authors who allow their wit to permeate their work. A superficial glance at the main body of my work might suggest that fun is not high on my professional agenda. What finally tipped the balance was that it might be fun. And finding a completely new voice to do it in might just make me a more skilled technician. Attempting a novel with someone else's infrastructure would certainly be different. My ambition for every book I have written – and there are more than 30 of them now, fiction and non-fiction, novels and short stories, for adults and for children – is that it should be better, or at least different from anything I've done before. The nagging voice asking who I thought I was – a mere crime writer – even contemplating taking on the divine Jane was all the encouragement I needed. Part of the reason was that I heard the old voices echoing down the years, saying, 'People like us don't do things like that.' Those eight words have been a constant spur to action for me: people like us don't get in to Oxford people like us don't become writers people like us don't do a whole raft of things I've tucked under my belt over the years.

Northanger abbey by val mcdermid