Four years ago when I first pitched the idea of a colouring book for grown ups to my publishers, they went understandably quiet. A couple of years later and with a million copies of Secret Garden sold around the world, the discussion for the 2nd book, Enchanted Forest was a lot easier!

So why are hard working adults getting to the end of a long day and reaching for the pens and pencils to unwind? For some people it's the nostalgic appeal of colouring. Chances are last time you spent some quality time with a colouring book life was a good bit simpler; no mortgage, no family politics, no worrying about global warming… Put the smartphone to one side, turn the TV off and allow yourself the chance to play again.

There's also the therapeutic effects of colouring. Personally, I experience a certain type of happiness, a sort of mindful and meditative state when I'm drawing and I've been told that's how people feel when they are colouring my illustrations. The act of being completely caught up in the task at hand, so the rest of the world just melts away. It's that sense of being 'in flow' that people find so soothing. I've received emails from a huge range of people from investment bankers to busy mums and those recuperating from illness, all saying the same thing - that colouring in offers them a great way to relax and de-stress.

Finally, there's the creative appeal. I believe everyone has a creative spark within them, they just need the opportunity and encouragement to let it flourish. A blank sheet of paper or an empty canvas can be daunting, but a colouring book offers a gentle buffer of sorts. I think of each page as a collaboration between myself and whoever owns the book; I draw the outline and they bring the colour. Sit down with a colouring book and you don't need to worry about composition or drawing, it's already taken care of. You just need to fill the page with colour and make your mark.

So next time your grandchildren reach for the crayons, why not get your own colouring book out and join them for an hour of creative time? For little people there's the chance to develop hand eye co-ordination and to talk about colours, for grown ups it's a wonderful way to be creative, unwind and of course do something with the grandchildren that doesn't involve an iPad or a screen.

Johanna's new colouring book Enchanted Forest: An Inky Quest and Colouring Book is published by Laurence King and will be available from 4 May on Amazon.

*Congratulations MamaCaz, you have won the signed coloring book! Please mail your address to [email protected] and we will post.*