Last year, Waterstones Piccadilly hosted a BookTok festival. One sales assistant told the Observer: “I can’t stress how much BookTok sells books. It’s driven huge sales of YA [young adult] and romance books, including titles such as The Song of Achilles by Madeline Miller and authors such as Colleen Hoover.

“The demographic is almost exclusively teenage girls, but the power it has is huge. We have a ‘BookTok recommended’ table – and you can tell which books are trending by the speed at which they sell.”