In the great scheme of things, few people really care about absolute authenticity, but I’m one of them. We notice the glaring anomalies, like the plastic water bottle on a recent photo of the Downton Abbey set, but to appreciate much of we see or read in historical fiction we would need to be extraordinarily expert in the details of the period. If hardly anyone will notice or appreciate the details, why do I spend so much time and effort trying to get it right? I do it because I love it; it gives me a smug satisfaction that I can defend the things I’ve portrayed and the words I’ve used. Earlier this week I was reading from ‘A Good Liar’ a conversation between my heroine and her mother about the respectability of the father of Jessie’s unborn child. ‘They live in Mikasa Street,’ Jessie pleaded, ‘They’ve got a bathroom!’. I couldn’t help myself, breaking off from the reading to assure my listeners that the houses in Mikasa Street (built by Vickers  in Vickerstown on Walney Island, named after a battleship in the Japanese navy) did indeed have bathrooms befitting the status of the workers to whom they were allocated. I beamed at them, they stared back. I’m sure none of them cared, but I did.

For more distant historical settings, the problem may be less acute, but many readers will have lived through my twentieth century settings themselves and will spot anachronism immediately. I was talking recently about the setting of my third book ‘Fallout’, in Seascale in 1957 at the time of the Windscale nuclear reactor fire. A lady in the audience told me cheerfully ‘Oh, yes, I was there that day’ and told me about watching the smoke streaming from the stack above the reactor building as she walked across the compound towards her office. ‘Which way was the wind blowing?’ I asked, but she couldn’t remember.

The setting for my next book will be around 1970 in the Furness area of what was then Lancashire and is now Cumbria. I’ve already spoken to people who worked in the newsroom of the Barrow-in-Furness newspaper at the time and next week I have a date with an ex-policeman from the same era. He laughed when I told him I was interested in the details of how it was to work in the force at that time: when the details are part of your own life you never think of them as important. But the details in my contact’s memory are gold-dust to me, and I shall listen hard, noting and remembering everything I can. How did the average copper think, talk and act at that time, before all the technological changes we have seen in the past 40 years? How did they relate to each other and to other ranks and parts of the service? Ian Rankin’s Edinburgh detectives call the men in uniform ‘woolly suits’: what were they called by their Barrow counterparts in 1970?

I know already that a large proportion of this authentic detail will never end up in the book. I’m writing a story, not a social history of the police force, and the pace can’t be bogged down by too much unnecessary information. I also know that the little nuggets of truth that emerge fresh and glinting into the text may delight only me and the few others who recognise their veracity. For most readers a few authentic details just add flavour to the image that springs from the words on the page. It could be the smell of something, a phrase or dialect word, a joke, a reference; anything can enhance the picture, like salt in food, taking it from the bland to the memorable. That’s what I’m after when I interview my bemused ex-policeman next week. By the way, all I did was send an exploratory email to Barrow police station: somehow, my request ended up on the desk of a Superintendent whose request for someone to respond carried sufficient authority that I heard back within days.

A year or two back, investigating the disaster in one of the Whitehaven pits in 1947 I came across the actual verbatim record of the enquiry into the disaster held by the National Coal Board at the time. It was tucked away in the archive of the Durham Mining Museum. Reading it was like there being there, and I managed to use just a word or two in the voice of one of the survivors. When the underground explosion happened, he said, they were some way from it but ‘the air fluttered’. What a wonderful phrase. Into the text it went and I love it still. Listening to my ex-policeman on Wednesday will give me the same delight, and hopefully the same treasure trove of authentic detail to mix into the story.