A self-published author has beaten names including Lee Child, James Patterson and Stieg Larsson to become the bestselling ebook author on Amazon.co.uk for the last three months of 2011, the online retailer said on Wednesday.

Kerry Wilkinson, 31, self-published Locked In, the first book in his Jessica Daniel series of detective novels, last year, only to find it shoot up the UK's Kindle charts. The three-book series has now sold more than a quarter of a million copies, with Locked In selling its 100,000th copy on Christmas Eve and becoming the top seller on Amazon's UK Kindle store for the last quarter of 2011. Kindle EU director Gordon Willoughby said the news was a "significant milestone" for independent publishing in the UK. Self-published author Katie Stephens also took the fifth slot over the same period with her debut novel Candles on the Sand.

"This time last year, I hadn't even started writing Locked In and now I have a No 1 bestselling book in the Kindle Store, outselling many authors that I have grown up reading," said Wilkinson. The author told the Guardian that he was only prompted to start writing fiction when he turned 30 in November 2010 and "decided I should probably do something with my life".

"I always thought I could create something – not necessarily a novel – and just thought I should do it. I'm not the type of person to sit around pontificating so, as soon as I had my idea, I just did it. Then I realised I actually enjoyed writing. I've got pages of notes left over and found I can write very quickly if I want to," he said.

"Once I had finished Locked In, I didn't really know what to do with it. I didn't write it for release as such, more as a test to myself. Then I saw the 'publish with us' button at the bottom of Amazon's website and just thought, 'What the hell?' I'm pretty good with computers and figured out the formatting and so on. Then I was away."

He priced the novel low, with a selling price of 98p, and keeps 35% of that; the later books cost £1.88 and £2.79, and Wilkinson keeps 70%. Sales began to take off when he released Vigilante, the sequel to Locked In. "With the reader's hat on, I never buy the first book of a series because, if I like it, I want to know there's a follow-up. When I released Vigilante, sales of book one soared. Locked In jumped into the top 10, then crept into the top five. When it got to No 1, it just stayed there. Then book two soared as well. I had the No 1 and 2 crime books at the same time with both titles in the top five."

Wilkinson never approached a traditional publisher with his novel because he "didn't set out to 'be an author'", instead aiming just to "write something I thought I would like".

"I keep chapters short and snappy because I like that. I try not to flit between characters too much because I don't like that either. As such, in a literary sense, I know it's not perfect - but I wasn't aiming for that. I wanted to create something I would like as a consumer," he said. "When I realised I could release it on Kindle, I bought one and thought about how they work. You can download 10% of the book for free as a sample. I cram as much as I can into that first 10% because I want people to read the sample and buy the book. I try to think like a reader because, basically, I am one."

Amazon's success with self-published authors in the UK follows the US arm of the retailer's announcement last year that two self-published authors, John Locke and Amanda Hocking, had sold more than 1m books on the Kindle. Hocking went on to sign a reported $2m deal with St Martin's Press, while Locke has signed up with Simon & Schuster.

With two more Jessica Daniel books due out this year, Wilkinson says he has an "open mind" about talking to publishers about his writing, with some already making contact. "I have nothing against the publishing industry at all. If they wanted to talk to me, I'd talk to them," he said.