While questions over writers' and publishers' attitudes to this type of fiction may be up for discussion, though, one thing seems pretty clear: A whole lot of people read self-published books.

"Looking back, I think Holy Island represented a ‘perfect storm,'" Ross said.

Ross said that everybody advised her against mixing those genres, and told her it would never work.

Ross said it's easier for books to "cross-fertilise" on Amazon KDP if you have a series, because of the way the platform signposts an author's other books.

"However you choose to market, I think it’s important to let readers know a little about yourself, so they can feel connected with the author and understand more about the person behind the stories they enjoy," Ross added.

"However, from speaking to and hearing from many other independent authors, I know that there are thousands of people out there who have been able to supplement their day job with a very healthy income, or work part-time as an author, alongside all of the other full-time indie authors who have been able to give up the day job. ?

SEE ALSO: 8 things I learned when I published my debut novel.

Like Ross, Abbott built on her initial success by serialising her books — bringing back her main character, Detective Chief Inspector Tom Douglas, for an additional nine novels.

"As a self-published author, even though my books are available in print, there was no one shouting about them (except readers) to bookshops," Abbott explained.

Abbott says successful self-published authors will make more money from their books than if they go through a traditional publisher — but that there are ups and downs to both approaches.

Horror author Adam Nevill is a slightly different case — although he's currently self-publishing his work, he wasn't always.

Nevill has been writing professionally for 20 years, and has 19 traditionally published books under his belt.

Nevill said he switched to self-publishing partly for financial reasons, and partly so he could have control over how his books are packaged and marketed?

After growing frustrated with dwindling author earnings and the publishing industry's perception of horror (Nevill described the genre as "outside comfort zones" in traditional publishing), he decided to make the switch?

"I took matters into my own hands in 2016," Nevill said?

"I will say I would have to go all the way back to 2013, when one of my trad' published novels had a London Underground campaign, to have matched The Reddening's level of sales," Nevill said.

"The Reddening is closing on becoming my fourth most successful novel, commercially, but in only four months.

It's my ninth novel but the only indie published novel; my other indie published titles are short story collections.".

"The best strategy I tried initially seemed both counter-intuitive and counter-productive and that involved producing free books and linking them to my website and author newsletter," explained Nevill.

"I feared devaluing my own writing, but in all of the courses I studied from professional and successful indie authors, they recommended this marketing strategy. .

Nevill said that when he has a book out, it's not unusual for him to work from 8 a.m

Being a successful self-published author clearly requires a huge time investment