What a way to go. As expat New Zealand artist Graham Percy lay dying in a London hospital in 2008, a nurse became concerned because he was frowning. She asked if he was in pain, to which the 69-year-old said, "No, no, I'm working out a drawing." As his body was shutting down, Percy's imagination was flying.

Percy's son Martin, who returned to New Zealand for the launch of Gregory O'Brien's new biography of the artist and a touring exhibition of his work, confirms the anecdote, related in the book, A Micronaut in the Wide World: The Imaginative Life and Times of Graham Percy.

"Greer Twiss [the Auckland sculptor and an old school mate of Percy's] made a very interesting observation at the opening," he says. "Even at school, Graham created the picture in his mind and then he executed it. He wasn't working it out on the paper - he worked it out mentally first, then bang!

"That's something people have commented on at the exhibition, partly because of the medium he was working in - ink on paper. If you get the line wrong, you've blown it, there's nothing you can do. So literally, his last act was to work that out and then he fell asleep."

O'Brien is doing Percy a great service in bringing his works to the attention of an audience who may never have heard of him. His graphic designs, children's book illustrations - including The Wind in the Willows and children's books about animals by Gerald Durrell - and a pair of fine late-career books of drawings made him a highly regarded figure in Britain and the United States during his lifetime. However, Graham Percy illustrations and children's books remain hard to get hold of in the country of his birth.

O'Brien and Martin Percy hope that will change.

But who was Graham Percy? O'Brien's early chapters tell of a boy born in 1938 in Stratford, a town which boasts 67 streets named after Shakespearean characters which "would prove ... not only a delectable paradox but a creatively useful one, particularly in the last years of his life".

Percy's mother died when he was 2; his school teacher father, George, who remarried a couple of years later and moved the family to Mt Eden in Auckland, died of heart failure in 1949 at the age of 54. Graham was 11. The book includes one of Percy's moving "childhood-memory" drawings (made in 2006) given to his younger sister, Joan. It shows a boy kneeling next to "the window seat - Kakariki Ave, Mt Eden". A little girl stands to his left and the words across the top say: "Graham, reading to Joan, from the newspaper the notice of Dad's funeral - as he does so, he starts to cry."

"I wondered if that was too personal to put in the book," says O'Brien. "The originals are in the exhibition. That's not the usual territory that someone would go into and that fascinated me - that he would return to those painful moments. It was the story of his family. The loss of his parents in some ways made him incredibly sensitive and he also needed to be very resourceful.

"Out of those sort of circumstances a sort of genius developed and he was always returning to childhood."

Martin Percy, a Bafta and Emmy-nominated interactive video director, says of the "Colin reading the death notice drawing" that his father was a "pull your socks up" man. "I think the way he deals with that is 'no use crying over spilt milk, now we are going to move forward type of thing', which was just him. He also had this heroic stepmother who he always regarded as his mother ... she made a fantastic job of it."

Percy's gift for drawing - despite the fact he was colour blind - was evident and encouraged from an early age, and after finishing his schooling at Auckland Grammar, he studied design at Elam. His friends and peers included Don Binney, Greer Twiss and Hamish Keith, with whom he set up a consultancy, Design Partners. As Keith recalls in the book, "We did an awful lot of talking" - but demand for their services was virtually non-existent.

So Percy trained as a teacher, taught art at Avondale College for two years, did temp teaching at Elam, and created some marvellously appealing drawings for the New Zealand School Journal.

Percy's career path shifted in 1964 when he was awarded a Queen Elizabeth Scholarship to study at the Royal College of Art in London for three years. Percy, his wife Lyndsay and 6-month-old baby Martin set sail in August. The direction of his life was about to change.

TWENTY-THREE YEARS ago, when O'Brien was in his 20s, he had never heard of Percy. But he had fallen in love with the work of Hungarian photographer Mari Mahr, who he says "was and is an artist of the calibre of Louise Bourgeois ... or even Frida Kahlo". He didn't know, at that stage, that she was the second wife of a New Zealand artist called Graham Percy.

O'Brien first discovered Mahr's work in 1988 when she held an exhibition at the Govett Brewster Gallery in New Plymouth, then at the George Fraser Gallery in Auckland. O'Brien, the Frank Sargeson Fellow at the time, was living above the George Fraser Gallery and went to gaze at Mahr's work every day, later writing her a fan letter.

To his astonishment, she replied and they started a correspondence, finally meeting in 2002 when O'Brien's wife, poet Jenny Bornholdt, was awarded the Katherine Mansfield Prize. That's how O'Brien and his family first met Percy, living with Mahr in a "marvellous house" in Wimbledon.

The two families met again in 2005, and O'Brien included some of Percy's School Journal illustrations in his book, A Nest of Singing Birds, to mark the journal's centenary.

"I became fascinated by his work," he says. "We had young children and we were loving the great licence that gives you to spend a lot of time looking at books written for children. People loved those drawings - I went around schools a lot with that book and people delighted in those pictures."

O'Brien included three Percy images in his next book, Back & Beyond: New Zealand Painting for the Young & Curious. Percy died a few days before the book arrived in the post in London. "Mari left the book, open at the pages with his drawings, on his work-table at home," O'Brien said at the show's opening at Wellington City Gallery. "She sensed his spirit was still hovering in the room, so he could check the pages out, comment to himself about the typography, folio, paperstock ..."

Shortly afterwards, O'Brien and Bornholdt were able to visit Mahr again in London en route to a writers' festival in France. The idea of a book on Percy's life and work was starting to foment. "There had been a memorial service for Graham at Elam in March 2008 - a lot of his old friends turned up, people like Hamish Keith, Wystan Curnow, Greer Twiss, Dick Scott, the historian. People brought things along and it was like a homecoming of a kind.

"At that point, Martin came out from England and we thought there was something there. Six months later Jenny and I were in England and with Mari, we went through the drawings - thousands of drawings."

The concept of the book had become feasible for O'Brien because his two earlier publications featuring Percy's work had won big prizes - the School Journal book won a Montana Prize in 2008 and Back & Beyond took the 2009 non-fiction children's book award. O'Brien quit his job as curator at Wellington City Gallery and the family moved to London to live in the Percy house, a 60s townhouse transformed by Percy's hand. "As well as working inside the house," writes O'Brien, "Graham worked on it, painting or drawing on just about every available surface ... with its constantly reshuffled contents, the house was a mechanism that generated material for Graham's art.

"We stayed at the house on and off for three months," he recalls. "It was getting inside what I was writing about, it was a fantastic creative cocoon. All the books referred to at the back [of A Micronaut in the Wide World] come from that house - you'd go to his book shelf and keep finding these little notes ... he had books that covered thousands of years and millions of miles. It was a real immersion thing, it was the only way you could have done it."

PERCY'S CAREER in London is too diverse and rich to recount here - that's what the book does so well - but once he retired from commissioned work - the children's books, mastheads for Harpers & Queens, book covers, British Rail billboards, a Royal Mail stamp design, an animated film called Hugo the Hippo in Hungary, where he met Mahr - "the lid came off", says O'Brien. Kiwis - the birds - started travelling the world in a charming series of drawings made in 2003-2005, and he reinvented New Zealand history in the 2005 Imagined Histories.

Later series, like the huge Alchemical Allotments and the Commedia dell'Arte, from 2007, are darker in tone. "They are very assertive, punchy statements," says O'Brien. "He was digging pretty deep inside himself. They are about fear and an awareness of mortality ... playing with ideas of the afterlife, some order in the universe beyond what he could see.

"I think he could be serious and playful at the same time. Most people can't do that. The Imagined Histories drawings are a beautifully played out intellectual game. They are funny, ironic and very affectionate. Never cynical, never detached, acts of love."

Two-thirds of the images in the book were made in the last five years of Percy's life and, says O'Brien, "his illnesses were such that he had to re-learn to draw twice in his life".

Percy first suffered a heart attack in 1993, losing the use of his right arm. It happened again in 2005 after he received chemotherapy for a form of leukemia. "In terms of dark periods, that was the darkest period," recalls Martin Percy. "With his final illness, I don't think that ever quite got him down. Dying is one thing" - he says, laughing - "but not being able to draw, that was serious trouble. So there was this odd period after the heart attack when his hand felt a bit floaty and that was a very dark time. But he practised and got on with it and it all came back."

Martin Percy would love to see the contents of the Wimbledon house come home to New Zealand. While Mahr lovingly preserves the house, its future remains unknown.

"The thing is with Graham," says his son, "is that he always regarded himself as a New Zealander and all his friends in London were New Zealanders.

"We've been preparing for this exhibition for ages - being with the drawings was not so much the big deal but being with the drawings back in New Zealand was. Graham grew up in Mt Eden and there's a friendly, unpompous Mt Eden lad at work all the way through.

"Then there's this interesting dialogue going on - this Mt Eden lad in conversation with this European, complex, high-culture sort of tension. Seeing all these New Zealanders who clearly understand it and comes to them naturally - I don't think that is quite the case for English people, who like them but wouldn't understand many of the references."

Perhaps the loveliest surprise about the book is that, having read it and fallen under what O'Brien calls the "Graham Percy spell", is to lift off the dust jacket and see a photo of the man himself.

"I think the book has a pervasive, inviting personality," says O'Brien, "which is that guy looking back at you from the book, doing what he does with love. We loved Graham immensely. He was an acutely intelligent person and he had that great humanity which you see in his children's drawings. There were no pretensions about him. He was an independent spirit."

Graham Percy
* New Zealand artist, born Stratford, 1938, educated at Auckland Grammar, Elam School of Fine Arts, Royal College of Art in London.

* Moved to London in 1964 where he forged a successful career as a graphic designer, children's books illustrator and book cover designer, and a prolific drawing career after retirement from commissioned work. He died in London in 2008.

* Art-directed 1969 animated film Hugo the Hippo, which still enjoys cult status; see hugothehippo.com

* For a video tour of Percy's Wimbledon house, filmed by his son Martin, see youtube.com
Discover more
In print: A Micronaut in the Wide World: The Imaginative Life and Times of Graham Percy, by Gregory O'Brien (Auckland University Press $59.99)

On tour: The Imaginative Life and Times of Graham Percy exhibition, which tours New Zealand over the next two years is at Wellington City Gallery until April 25, and opens at the Gus Fisher Gallery, Auckland, on May 7