A book by Seuss that was of no use is now on the loose.

Key points: Notes and sketches for a new book were discovered by Dr. Seuss's widow

Notes and sketches for a new book were discovered by Dr. Seuss's widow Experts believe they were done as far back at the early 1950s

Experts believe they were done as far back at the early 1950s Australian artist Andrew Joyner was sworn to secrecy after being asked to finish the drawings

More than two decades after famed children's writer and illustrator Dr. Seuss died, a manuscript for a long-lost story was unearthed.

And after a global search for an artist worthy of the task, Australian illustrator Andrew Joyner was tapped to bring it to life.

"I couldn't have imagined that this type of job would come to me," Joyner told the ABC.

"I loved Dr. Seuss when I was a kid growing up in the '70s — it still seems slightly surreal that I got the opportunity."

Andrew Joyner's partly illustrated cover. ( Supplied: Andrew Joyner )

60 years in the making

Dr. Seuss — aka Theodor Geisel — was the bombastic and absurdist storyteller who delighted readers until his death in 1991.

Yet it wasn't until 2012 when his widow, Audrey, was going through his studio that she stumbled upon a treasure trove of notes and sketches for a missing book, The Horse Museum.

Joyner's work was based around existing Dr. Seuss notes. ( Supplied: Random House )

There was no official record to go with the drawings, but experts believe they were done as far back as the early 1950s.

The story follows a horse as it guides a group through a museum looking at the real-life examples of how artists have imagined the humble horse.

It includes reproductions of more than 30 artworks about horses, from artists like Pablo Picasso to Susan Rothenberg and Jackson Pollock.

The book mixes the real with the really absurd. ( Supplied: Random House )

And there are cameo appearances from beloved Dr. Seuss characters, such as the Cat in the Hat and the Grinch.

It's not the first time a Dr. Seuss book has been posthumously produced, with What Pet Should I Get? discovered in 2015, having believed to have been written between 1958 and 1962.

That long-lost literary gem was also discovered in a search of old material in his California home.

Sworn to secrecy

Joyner is no novice when it comes to illustrating children's books, having earned acclaim for his work on bestselling works like The Terrible Plop and Too Many Elephants in This House.

But it was his work on a book called The Pink Hat that drew the attention of publishers in the US.

Joyner has already experienced international success. ( ABC News )

"I just think there's something in my style, probably because I grew up and loved Dr. Seuss — I don't draw exactly like him, but there's some element of his work that has influenced me," he said.

Joyner signed the contract and was sworn to secrecy, with not even his closest friends aware of the work he was doing.

"It was good to work on it in secret," he said.

"I think I would have found it very hard to work on it if I was thinking about the gravity of the job."

Joyner's style was already on a similar level to Dr. Seuss'. ( Supplied: Random House )

Joyner grew up on a diet of Dr. Seuss and names some of the more iconic titles among his favourites: Oh, The Places You'll Go and The Cat In The Hat.

It was the cat that was forefront in his mind as he set about the work, done entirely on an iPad, that attempted to paint a Seuss-esque picture while also working around other artists and their horse images.

Rather than be daunted by the task, Joyner said it helped him.

"Because I had to draw my illustrations around artworks by people like Picasso and Dali and things like that, it provided a nice sort of restriction to work with," he said.

"Illustrators love restrictions, really. We don't want a completely blank canvas."

Joyner was still able to add his own flair. ( Supplied: Random House )

As for why Dr. Seuss has such lasting appeal, Joyner said he had a charm that was impossible to fake.

"That's a really elusive aspect and something really hard to capture, or hard to manufacturer anyway, but he just seemed to have it," he said.