The  chance discovery of diaries depicting the horrors of war through the eyes of a boy soldier inspired the book that has won this year's highest honour for children's literature.

Matt Elliott, a comedian and author, wrote Nice Day for a War after finding his grandfather Cyril's diaries from World War I.

The book, part graphic novel, part historical novel, was illustrated by Chris Slane, and won the New Zealand Post Book of the Year at a ceremony held in Wellington last night.

Convener of judges Gillian Candler said the book combined elements of graphic novels with powerful, emotionally engaging narrative.

"Beautiful, loose, fluid, line drawings and muted watercolour washes make Cyril's war diary come alive. The interplay between visual language and text to engage and inform readers is exemplary.

"[It] offers young readers a glimpse into the lives of soldiers during World War I and doesn't gloss over the horror or the boredom of war. But neither does it set out to shock or disturb."

Wellington children's writer Jack Lasenby won the Young Adult Fiction category for his novel Calling the Gods, the story of a teenage girl who is banished from her home in an alternate world.

For more than four decades, Lasenby has been writing children's books, short stories including Harry Wakatipu and Uncle Trev, as well as young adult novels that include The Lake and The Mangrove Summer.

"Calling the Gods is a masterful work that transcends genre and can be read with pleasure at many levels," Ms Candler said.

Lower Hutt writer Barbara Else received this year's honour award for The Travelling Restaurant, a children's novel following the adventures of a young boy as he sails on a boat called The Travelling Restaurant.

Wellington writer Chris Szekely's book Rahui, which was published in both English and Maori, won best picture book.

It is illustrated by Malcolm Ross and tells the story of cousins holidaying at a beachside community and the rahui – temporary ban – placed on the beach after a death.

"Both versions of this beautiful book have a timeless quality. A difficult topic in some hands, this story deals sensitively with the sad drowning of a cousin," Ms Candler said.

THE WINNERS

Non-Fiction category and New Zealand Post Book of the Year

Nice Day for a War by Matt Elliott, illustrated by Chris Slane.

Honour Award

Digging Up The Past: Archaeology For The Young & Curious by David Veart.

Junior Fiction category and Best First Book Award

Super Finn by Leonie Agnew.

Honour Award

The Travelling Restaurant by Barbara Else.

Young Adult Fiction category

Calling the Gods by Jack Lasenby.

Honour Award

The Bridge by Jane Higgins.

Picture Book category

Rahui (Maori version) by Chris Szekely, translated by Brian Morris, illustrated by Malcolm Ross.

Rahui (English version) by Chris Szekely, illustrated by Malcolm Ross.

Honour Award

Shaolin Burning by Ant Sang.

Children's Choice Award

The Cat's Pyjamas by Catherine Foreman.

- © Fairfax NZ News