The people have spoken. The verdict is in. And Then There Were None has been voted the world’s favourite Agatha Christie novel.

As a fervent believer in democracy I hate to say this, but the world has got it wrong. Yes, the winning title is clever, cunning and compelling. But it’s too improbable for me. It’s the kind of locked-room mystery that I can admire but not love.

When it comes to the best Christie, as opposed to the most popular, my vote still goes to The Murder at the Vicarage, the novel that introduces the estimable Miss Marple. Written at the height of Christie’s powers, it’s perfectly constructed, packed with red herrings and smart sub-plots; it’s shot through with sly humour; and it’s full of characters who may be stereotypical but whose motivations and responses we recognise, often with a wry smile.

It’s possible I may be biased in my assessment, for it was The Murder at the Vicarage that made me a crime writer.

As a child, I spent a lot of time in my grandparents’ house. I would always arrive with an armful of library books but more often than not, I would run out of reading material. My grandparents were not readers; they had a Bible, of course, but inexplicably, they also had a battered paperback of The Murder at the Vicarage.

Linguistic scientists tell us that a reading age of nine is sufficient to comprehend Christie, and I was a precocious reader. From the age of seven or so, The Murder at the Vicarage became my default reading, the pages I returned to when I’d finished my library stockpile. I fell in love with the complicated intersecting narratives, the recognisable claustrophobia of village life – even in a Scottish mining village, there were parallels – and the cleverness of Jane Marple herself.

When I realised that Agatha Christie had written more than one book, it became my mission to work my way through all of them. I haunted jumble sales, I discovered secondhand bookshops, I stole my mother’s library card so I could access the adult shelves. That was where it dawned on me that there were other writers who wrote detective stories. (I worked it out from the famous logo of the Collins Crime Club – a masked skull brandishing a pistol.) And I was enthralled.

We sometimes hear of cross-species adoption where orphaned animals bond with a very different creature and take on the characteristics of the adoptive animal. I think something similar happened to me with Agatha Christie. I read The Murder at the Vicarage so frequently that embedded within my brain is the notion that grown-up books have to have dead bodies in them.

The stakes are higher when it’s a matter of life and death: the adrenaline surge we get as readers is stronger. There are moments in this novel where we feel both pity and a genuine frisson of fear. Christie is often criticised for her cardboard characters and there’s some truth in that, particularly in the later work. But when she’s at her best, as she is in The Murder at the Vicarage, her characterisation is pointed, economical and often sharply satirical.

Here’s how we’re introduced to our heroine: “I … sat down between Miss Marple and Miss Wetherby. Miss Marple is a white-haired old lady with a gentle, appealing manner. Miss Wetherby is a mixture of vinegar and gush. Miss Marple is much the more dangerous.” And a few lines later, we meet Miss Hartnell who is “weatherbeaten and jolly and much dreaded by the poor”.

We can see these people, hear them and know them. For a writer starting out, that ability to nail people in a line or two was a valuable lesson to learn. The plotting too, obviously. Those interwoven story arcs, each with a set-up, development and pay-off (often an unexpected one) taught me much of what I know about the black art of narrative. It’s no exaggeration to say that The Murder at the Vicarage set me on a path I’ve been happy to follow for 30 years.

People, you got it wrong.

• Val McDermid’s latest novel, Splinter the Silence, is published by Little, Brown