All across Europe bookshops are experiencing a steady growth in the sales of colouring books, thanks to a new fan base.

No longer just for children, colouring books are increasingly bought as a de-stressing tools by adults.

According to the Telegraph, sales in Waterstones have increased by 300 per cent between Christmas 2013 and 2014, following a trend which began in mainland Europe.

Melissa Cox, head of children's buying chain, explained the sudden interest in colouring:

"It’s a trend that started in France and has been very popular with French women. It’s a relaxing thing to do, especially when you’re on the phone a lot. People say it’s proven to help you relax."

As a result of the more advanced consumers, demand is increasing for books with more intricate and challenging designs.

Mohara Gill, Head of Art at Foyles, another British book store chain, said that displays for colouroinf books had been expanded due to  their rising popularity:

"Colouring books are great if you're interested in 'creativity' but don't know where to start. They’re also very therapeutic...

"We have expanded the range since we moved to 107 Charing Cross Road, from half a shelf at 113 to three and half shelves at 107. In addition our general section on 'Creativity' (Doodling, Zentangling, Journaling, colouring Books) has increased from two shelves to a column reflecting the increased popularity of the subject."

In mid-2014 the Telegraph reported that French publishers Hachette and Marabout had sold around 650,000 copies of colouring books between them.