The Duke and Duchess of Cambridge have said talking openly about mental health can remove “stigma, fear and isolation” as they welcomed a children’s collection of puzzles compiled by Britain’s master codebreakers.

Publisher Puffin has teamed up with GCHQ to produce Puzzles For Spies, and William and Kate have written a foreword for the book.

Proceeds from GCHQ’s share of the advance and royalties for the book, estimated in the first year to be at least £20,000, will go to The Royal Foundation of The Duke and Duchess of Cambridge to support its mental health work.

Puzzles For Spies introduces readers to many aspects of the work GCHQ do and includes codes and brainteasers, word riddles and language puzzles, plus personal accounts from GCHQ staffers.

It is hoped that young readers of the book will discover a discipline or role to match their skills and strengths and see the importance of teamwork and a diverse range of minds in achieving a common goal.

GCHQ has previously created two puzzle books for adults – The GCHQ Puzzle Book and The GCHQ Puzzle Book II – which have sold half a million copies between them.

In the foreword, William and Kate say: “We are delighted that the brilliant minds at GCHQ have been busy working on a third puzzle book, and that this edition is designed for younger readers.

“Hopefully this might mean we find them easier to solve…!

“As a family, we are no strangers to the vital work of GCHQ. We have seen first-hand how staff constantly adapt to face new threats, and we remain inspired by how committed staff are to protecting our national security.

“The Covid-19 pandemic presented one of the biggest global challenges in recent history. It impacted our ability to go to work, to school, and to socialise in the way we are all accustomed to.

“This affected every one of us and sadly we know the true scale of the pandemic’s impact on the nation’s mental health will not be fully understood for years to come.

“Your support through the purchase of the book will ensure that the Royal Foundation is able to continue its mental health work at a time when that support is needed more than ever before.

“We look forward to helping our children solve these puzzles, and hope that this book brings friends and families together to start rich conversations.

“Talking openly about mental health can be the first step in removing stigma, fear and isolation.

“Just like at GCHQ, bringing different perspectives together can often be the key to unlocking a solution you can’t quite find on your own.”

In his foreword, GCHQ director Sir Jeremy Fleming said: “While problem-solving exercises our brains, it is equally important to take care of our minds.

“Our first two books raised a staggering amount of money for mental health charities and enabled them to do valuable work in communities across the country.

“I’m delighted that through this book we will continue supporting this cause.

“The work of Their Royal Highnesses has helped many people – including children – be more open about mental health.

“I want to thank them for both their ongoing commitment to this cause and their support to GCHQ.”

The book will be published on September 22.