Engraved into a headstone in the graveyard of St Mary The Virgin Church in Burpham, West Sussex, is the line “to live at all is miracle enough”.

Its beauty (albeit bittersweet) is in being set in a place where lost souls search for redemption in another world rather than on Earth.

The only sorrow, surely, is that so few people get to see the eloquent, edifying epitaph, because it is tucked away among a scattering of flint cottages in rural, watery Downland.

Yet the elegy suits its location: the village has a rich literary history. John Cowper Powys was brought up there, and naturalist Reverend Tickner Edwardes, whose gift to the world was The Lore Of The Honey-Bee, is buried in St Mary’s graveyard.

Not far across the grounds of the 11th-century church, with its striking Norman arch, are the remains of Mervyn Peake, who penned those words.

He is a towering figure in the literary world, chiefly remembered for the Gormenghast Trilogy, which focuses on life in the eponymous castle, home to the Groan family who have ruled it for more than 70 generations.

He had his first story published when he was only eleven years old; by the time he died aged 57 in 1968, after a long battle with Parkinson’s disease, he had had success as a novelist, illustrator, painter, poet and playwright. This year would have been his centenary.

The anniversary has renewed interest in a man whose work was seemingly forgotten after a BBC TV mini-series adaptation of Gormenghast, starring Jonathan Rhys Meyers, flopped in 1999.

To make amends the BBC has commissioned Brian Sibley to serialise the Titus Books for six hour-long shows – The History Of Titus Groan – planned for BBC Radio 4 in July.

Sussex played a vital part in Peake’s early career as a writer; he lived for a time with his parents in Wepham, a hamlet a stone’s throw from Burpham, and returned regularly to visit his brother.

Attention is about to return to the region with aficionados from across the world descending for the first ever Mervyn Peake Conference, organised by the University of Chichester and the Sussex Centre For Folklore, Fairy Tales And Fantasy, in July.

Guest speakers include Peter Winnington, author of Peake’s authorised biography, and Sebastian Peake, Mervyn’s son, who now administers the Mervyn Peake Estate with his sister Clare Penate (who, coincidently, is mother to singer Jack Penate).

Peake’s nonsense and poetry illustrations, including The Hunting Of The Snark and Rhymes Without Reason, will be on loan from his estate for an exhibition at the university’s Otter Gallery opening May 26.

Across the city, at Pallant House Gallery, visitors have the chance to see a collection of Peake’s illustrations which, as with those at the Otter Gallery, were originally brought together for a show at Maison d'Ailleurs in Switzerland. This is the first time they have been put together for a UK show.

“We are showing another side to him,” says Julie Brown, the curator at Pallant House Gallery who put the show together. “His fiction is well known. But his drawing and etching skills, his brilliant, genius-like illustrations, are almost undiscovered.

“There are people who think they know Peake’s work, but they might not realise he was multi-talented. Others, who know nothing of him, will be delighted to discover another of the nation’s artistic treasures.”

The gallery is making a name for itself as something of a regional powerhouse in modern British and European art.

In 2006 its breezy new wing opened. It is filled with colourful pop-art from the permanent collection and an exhibition showcasing Robin and Lucienne Day’s classic interiors.

Such is the strength of the gallery’s collection that the 70 Peake works are housed upstairs in a compact, domestic-style space in the original townhouse.

Complete with antique fireplace and authentic creaking floors, the room feels unchanged since the building was first constructed in 1712.

Finding it feels like searching for the Peake’s burial place in deepest Burpham. But Brown is on hand to help, flanked by Peake enthusiast William Gray, Professor of literary history and hermeneutics from the University of Chichester.

It was Gray who first approached the gallery to join the centenary celebrations. He was essential in the exhibition’s gestation, and as we climb the stairs he can hardly contain himself.

The exhibition is as rewarding as the inscription on Peake’s gravestone. There is humour and pathos. It displays a range and diversity of technique, flashes of brilliance, executed with fastidious precision.

Some of the creations even seem to have a pulse.

“It is the mixture of styles which really blows you away,” says Brown. “His illustrations for Robert Louis Stephenson’s Treasure Island show you he had that rare gift for capturing movement. He highlights how apparently simple straight lines can depict energy and direction through fine variations in thickness and weight.”

The curving lines which carve space in the illustrations of falling seaman, Israel Hands, are the perfect example.

Sometimes lines are omitted altogether and implied with shading. In one where Long John Silver pulls on a rope with his teeth, Peake used shading in place of an outline: the continuous line of the rope is shown by a series of very short lines at various angles and of varying thickness.

Gray says Treasure Island was Peake’s favourite book when he was growing up. Because he loved it so much his illustrations were incredibly sensitive to the characters. He had a rare ability to put himself into the heads of Stephenson’s creations, to imagine their world, to give them new life and add to the text; he picked up on moral and sexual themes others had missed. His designs are nowregarded as preeminent, and Stephenson would have approved.

Another of Brown’s favourites, Our Lady’s Child, from Household Tales by the Brothers Grimm, shows Peake’s extensive skills. The series evokes the sombre and ominous brooding of Goya or works by Gustave Doré.

Printers Eyre & Spottiswoode commissioned Peake to produce 60 pen and ink drawings, including five colour plates, for the first collection of the German folk tales by the brothers Jacob and Wilhelm in 1812.

The works are not large. You need to get up close to really appreciate his handiwork and dexterity.

“His interpretations were applauded as the finest since those of Cruikshank,” says Brown. “They are a good example of his range of techniques: pure and clean single lines to create a striking sense of volume, and cross-hatching and dots which make his drawings look more like engravings.”

Iconographers trace this style back to China. Peake was born in the country in 1911 to British Congregational medical missionary parents. They supported his wish to write and draw, and from an early age employed a calligrapher to teach him Mandarin characters.

When he was 12, he was sent to Eltham College in London. The epic journey by sea, via the Cape to England, inspired one of his first illustrated children’s stories, Mr Slaughterboard, and a lifelong love of pirates and buccaneers. For Professor Gray the centrepiece of the exhibition is Captain Slaughterboard Drops Anchor.

“It is both sinister and humourous, and clearly influenced by Japanese artists – people such as Utagawa Hiroshige.

“The interesting thing about Peake, and this series in particular, is that he created characters through both his text and his pictures. It was the two coming together, the symbiosis. He might begin to describe a character with words but it would relate to the illustration he had in his head, and vice versa.”

That holistic approach bred fulsome characters. Captain Slaughterboard is a feared plunderer who discovers a pink island with unusual inhabitants. He befriends a yellow creature, who encourages him to change his dastardly ways, to embrace a new, peaceful and contented life on the island and the two eventually fall in love.

There is hot discussion between eminent etymologists about the origins and influences at work in Peake’s writing.

His first son Sebastian, born in a seafront nursing home in Littlehampton in 1940, believes those early days in China were vital. He also says Sussex provoked many of his father’s thoughts.

Sebastian’s childhood was transient because Mervyn was restless, and every six months there would be another move. But the family spent a notable time in Wepham in the cottage his parents rented from the Duke Of Norfolk before they moved to Sark. Another of the Duke’s larger properties looms over the River Arun, which ran past Peake’s front door.

“I am sure he took inspiration from looking at the outline of this fantastic castle,” says Sebastian. “Arundel Castle is one of the great castles of this country. I think he might well have been inspired by that, certainly the flint in the landscape, which is ubiquitous in that part of Sussex.”

Another view, proposed by expert Peter Winnington, is that nothing in Titus Groan is sufficiently precise for two readers to agree on; Peake was a writer whose sources lay not in the outside world but in the imagination.

To crown the centenary (and perhaps muddy the waters further), the final Gormenghast book, Titus Awakes, written by Mervyn’s widow and Sebastian’s mother, Maeve Gilmore, is to be published. The novel, based on two pages and notes left by Peake, completes the sequence.

“In a way the dénouement of the whole piece is that Titus, in the end, wants to find a home and to come to rest,” says Sebastian. “My father’s books were based on somebody who never will find a home.

“But my mother wanted to round it off, as it were, in that Titus goes through her own memories of real people in real life. She introduces Titus to them. Then in an explosive short four-page chapter she has him go to work in hospital and there in a bed is my dad, who is an artist lying prostrate, because he was like that in real life.”

One of the last things Peake ever wrote was “search without end”. Yet in Gilmour’s concluding work, which has been hidden in a south London attic since she died in 1983, Titus realises he wants to end up on an island.

“It’s fitting,” says Sebastian. “It is where my dad found his happiest time.”