More than 1,300 writers including Kerry Hudson, David Nicholls, Sally Rooney, Michael Rosen and Val McDermid have backed a campaign for Waterstones booksellers to be paid the living wage.

The support follows a petition from staff at Waterstones, signed by more than 6,000 people, which calls on the book chain’s managing director, James Daunt, to pay booksellers a starting living wage of £9 an hour, or £10.55 for the Greater London area. “Working for a rate of pay that is below the living wage results in booksellers who are stressed, preoccupied and who have little spare time and energy to devote to buying books, reading them, and keeping up with news and trends in the industry – all of which activities are undertaken outside contracted hours, and which many staff consider to be (and are encouraged to view as) integral to their role,” says the petition.

On Monday afternoon, Hudson, author of the acclaimed memoir Lowborn, launched an open letter from writers supporting the Waterstones staff position. It now has 1,340 signatures from writers of all genres including poet and Scottish makar Jackie Kay, children’s authors Frank Cottrell-Boyce and Juno Dawson, crime novelist Holly Seddon and science fiction and fantasy writer Jon Courtenay Grimwood.

“As authors, we recognise the vital role booksellers play in our literary culture and industry. Their skill, expertise and passion are a true asset, and this deserves to be acknowledged both through public recognition and financial remuneration,” the authors write. “There is anxiety from staff members about the potential for an increased wage being subsidised by staff redundancies or reduced hours. We wish to make it clear that authors will not support that as an outcome. A business that cannot offer a living wage to staff without redundancies or reducing hours [does not have] a viable business model.”

Hudson told the Guardian that she had not been surprised by the level of support for the letter. “It’s not easy to stand up and ask for something like that and we wanted to add our voices to their courageous stand. I was shocked, as I think many were, to learn that this was not a standard at Waterstones,” she said. “While I appreciate there are many complexities in running a business, it feels that leaving those doing the frontline work to choose between, as one ex-staff member told me, ‘food and bus fares’, cannot be right.”

In an open reply to Hudson, Daunt said the writers were “preach[ing] to the converted”, but that the book chain could not yet afford a pay increase, two years after returning to profit: “A progressing pay structure based on a floor of the real living wage is highly desirable. If we can continue to grow profitability, this will be possible.”

The managing director of the UK’s largest book chain told the Guardian on Tuesday that “there’s a long gap between wanting to do something and it being remotely sensible”. Waterstones is committed to a “progressive pay scale”, promoting and paying more as booksellers gain experience.

“If you raise the bottom level really significantly, then everybody all the way up the company has to go up, and then we go bust, which isn’t very helpful,” he said. “If we were to move to a significantly higher starting rate, then we would have to take that money from our more experienced booksellers, or cut costs in another dramatic way. We’re simply not profitable enough to wave the magic wand and shower gold all around.”

He also disagreed with the notion that not paying a living wage meant the business was not viable. “You’re saying we would be better off closing down than running the pay structures we are?” he said. “For me, it’s how do you best advance salaries as a whole. You’d always want to have as high a base starting rate as you can, but it’s really important to have career progression and pay advancement through the company. That’s something we’ve been investing in.”

Daunt was clear that he “wouldn’t for one second suggest that a career in bookselling is a career paved in gold”.

“To retain the best and most talented booksellers, we have to reward them, and we reward them as well as we can with pay, but we mainly reward them with a stimulating job,” he said. “I would maintain that we have made some pretty good advances, which have brought us to a place where we are financially secure, which is just as well given the environment we are in.”

Waterstones said that of other similar large retailers, only Ikea, Majestic and Lush commit to paying the real living wage. On Monday, Majestic Wine announced it will close a number of its stores and focus on its online and international business.