Attendees at the London Book Fair heard how Britain’s looming departure from the European Union has raised fears about the impact on those who make (some of) their living from writing.

“Because the details haven’t been worked out yet, it’s hard to know what is coming next,” said Francis Bickmore, a director at Canongate, a Scottish publisher. “I think we’re sort of in denial.”

The fears stem from a looming fight with US publishers over sales in Europe. For decades, EU trade klaws allowed British booksellers to dominate English language sales across the continent. It turned the UK into the largest book exporter in the world, with annual sales of $6.8 billion.

If Brexit brings extra tariffs or restricts sales, the fallout could be huge.

At the Frankfurt Book Festival, Simon & Schuster’s chief executive, Carolyn Reidy, told an audience that, after Brexit, “the argument the British have used to grab Europe as an exclusive market will then be over.”