Roald Dahl's original sketches, created for his memoir, will be sold at auction after being found in an envelope.
Dahl, who was born in the Cardiff suburb of Llandaff, produced the sketches in black ballpoint pen for the book Boy, which was published in 1984.
He died in 1990 aged 74, and in his almost five-decade long career, these are the only book sketches he ever produced.
The sketches will be sold in Edinburgh as part of Lyon & Turnbull's books and manuscripts sale on 18 June.
The sketches are part of a collection estimated to sell for between £20,000 and £30,000.
In his memoir Dahl recalled various childhood exploits, including playing a prank with his friends on the local sweetshop owner Mrs Pratchett by putting a dead mouse in a gobstopper jar.
To illustrate to prank, Dahl drew a mouse lying on top of the sweets with its legs in the air.
The drawings were found in an envelope marked "Dahl's drawings & odds and sods" which belonged to Ian Craig, the art director at publishing house Jonathan Cape.
Mr Craig, who died in 2023, created the final illustrations for the book inspired by Dahl's drawings.
He also oversaw the production of the book and the archive includes his designs, as well as the original page layouts and correspondence.
Mr Craig came up with the title, and received a letter from Dahl saying: "I must thank you for coming up with the first sensible title for my book. 'Boy' is fine. We all like it…"
His widow, Kate Craig, who also worked at Jonathan Cape, said the publication of Boy was "on a very tight publication schedule".
Dahl's usual illustrator, Quentin Blake, was "away on holiday," she said, so "Ian asked Dahl if he could help with the illustrations".
"Dahl ended up producing a variety of sketches which Ian used as inspiration for his own drawings.
"Ian never got paid for the illustrations, but Dahl did give him one of his trademark blue cashmere cardigans as a thank you, which he treasured."
Dominic Somerville-Brown, Lyon & Turnbull's rare books and manuscripts specialist, said: "It's absolutely thrilling to see Roald Dahl's one-of-a-kind, hand-drawn sketches up close.
"They are a unique addition to his canon and allow us to observe the transformation of his childhood memories into the printed form, a medium in which they would be cherished by generations of readers.
"Ian Craig undoubtedly played a key role in Dahl's publishing success, overseeing not only the production of Boy, but many more of his famous children's stories.
"This archive gives an insight into the creative processes behind a book still enjoyed by children across the world today."