Discworld. Used with the permission of the Trustees of the Josh Kirby Estate.

Prepare to have your mind blown out of this world at a new exhibition celebrating the fantasy artwork of Josh Kirby, the acclaimed illustrator behind Terry Pratchett’s Discworld book covers and the film posters for the Star Wars: Return of the Jedi and Monty Python’s The Life of Brian.

Out of this World: the Art of Josh Kirby is showing at Liverpool’s Walker Art Gallery until September 30 2007, and is the first major retrospective of this Liverpool-born artist who died in 2001.

The exhibition spans Kirby’s entire career, from his early days as a freelance artist creating covers for the pulp fiction and film posters of the 1950s to his regular book cover commissions for publishers such as Corgi, the most famous and most recent of which is Pratchett’s Discworld and Eric/Faust series of fantasy books.

Return of the Jedi, 1983. Used with the permission of the Trustees of the Josh Kirby Estate.

Kirby had decided by the time he turned seven that he wanted to be an artist and was registered at the Liverpool City School of Art in 1943 at the age of 14, staying until 1948. These five years gave him a traditional grounding in a wide range of art disciplines.

It was at the Art School that Kirby was nicknamed ‘Josh’ after his portraiture was likened to the great master Sir Joshua Reynolds. The name stuck and his birth name, Ronald William, was rarely used again.

It seems that because of his technical skill and draughtsmanship, Kirby could soon command work in almost every genre, including commercial and film advertising, computer games and games books and even supplying artwork for jigsaw puzzles in the 1970s.

The exhibition features over 200 exhibits covering a breathtaking display of Kirby’s work, from a group of highly worked watercolours that were probably painted while he was still at college to his most famous iconic images including a portrait of Alfred Hitchcock and the cover of L Ron Hubbard’s bestselling 1982 science fiction novel, Battlefield Earth.

Rolling Gravestones, 1973. Used with the permission of the Trustees of the Josh Kirby Estate.

Since Kirby often made a duplicate of the work that he sold to have a copy to keep, it means that you can see a virtually unbroken train of artwork representing his entire career. It’s possible to see how his style developed from his early years and to marvel at the way his imagination quite literally took flight.

Although fantasy artwork is usually associated with airbrushing, nearly all of Kirby’s work is painted by hand in oils. It’s this that gives them a sumptuous and vivid richness and a staggering level of meticulous detail.

The exhibition also includes a series of paintings of deep personal significance to Kirby, including the Voyage of the Ayeguy. These paintings chart the epic voyage of ambassadors from the Ayeguy civilisation and are widely regarded to be his tour de force. Kirby continued to add to the series right up to his death.

Monty Python's Life of Brian. Work reproduced here with the co-operation of Python (Monty) Pictures, and with the permission of the Trustees of the Josh Kirby Estate.

Without doubt, though, it’s in the Discworld series of paintings that Kirby could really give his imagination full rein. And although he owes a debt to Bosch and Bruegel, the vision he created here is most definitely his own.

It’s pretty telling that Terry Pratchett himself said: “I only invented the Discworld. Josh created it.” After that first lucky commission from Corgi back in 1984 for The Colour of Magic, a magical partnership was cemented and Kirby was pretty much given free range to interpret Pratchett’s fantastical worlds.

It was a partnership that was to span 15 years and 26 novels – for novels that Kirby described as “Bruegel in literary form”.

Whether you’re a science fiction or fantasy lover or not, this exhibition is sure to take you to another world.