It's halfway through Norman Gilbert's exhibition of his life's work and he's not entirely sure how to feel about it.

"Proud?" he says questioningly. "It never really entered my head to be proud, but I'm always glad when people like it."

On a dreich Friday in Glasgow, a very modest 90-year-old Norman is at home where he's happy, painting a picture of his back door which makes him even happier.

For the last week, 65 years worth of his paintings have been on display at the Sutton Gallery in Edinburgh, a retrospective of a remarkable body of work and an equally remarkable story.

Norman was nine years old when he arrived in Scotland. The son of Scottish parents he had been born abroad in Trinidad, a Caribbean island of jewelled hummingbirds and mangrove swamps.

In 1944 he joined the Royal Navy, on a boat bound for Japan. He was just 17 years old and the bombs had been falling since he was a boy.

Yet time was on his side and before his ship could reach eastern waters, the bombing of Nagasaki and Hiroshima brought the war to an end.

For two and a half years he sailed the Mediterranean instead, but there was a niggling inside him that just wouldn't budge.

"I think he wanted something that would last beyond his lifetime," says his son, Danny.

"And he did. He found something that has been his definition of himself for 65 years."

Norman followed his passion and enrolled in the Glasgow School of Art though immediately found himself at odds with the style of painting being taught.

Described as "unteachable" he ploughed on regardless with his own style, so much so, he was refused his diploma at the end of his four years at the school.

Instead, he found love. "A classmate called Pat," he says, his voice warming.

"We'd been in the same school for two years and didn't really pay any attention to each other."

Until one day, the class went on a trip to a dairy and Norman and Pat shared their first proper conversation over a bottle of milk.

"We were exchanging notes on what we'd done during our holiday, she'd hitchhiked to Rome and I was very impressed," says Norman.

"That sort of did it."

Impressing her in turn with his stories of forays up Glasgow cranes to draw the city below, Norman and Pat built a relationship to last.

Pat would stick by him throughout his career, even during the toughest times.

The couple lived with their first baby in a caravan where Pat had the second of their four sons and Norman found a job looking after pigs while continuing to paint in his spare time.

Later he worked as an art teacher in Dumbarton but was paid half that of other teachers because he had not got his diploma.

By the time his third son was on the way, Gilbert realised his situation had to change if he was to survive as both an artist and a father.

He went back to school to resit his final year and finally walked away with the bit of paper he needed to get on with the rest of his life.

In 1966 he had his first one man show in London's prestigious Upper Grosvenor Gallery.

The same year Vogue magazine published a feature on his work.

"It was a case of painting what came to hand," says Norman. "When I had a family here I used them as models and when my sons grew a little bit older and started to bring their girlfriends round I painted them too.

"Then when they all left, I moved onto the garden and began painting what I saw there."

Inspired by the French artist Henri Matisse, whose book he used to carry around with him, Norman's paintings are similarly vibrant, filled with rich colour and intricately decorated patterns.

Soft pinks and pale duck egg blues create a tranquil feel in his work, with people, plants and flowers all circling each other in harmony without the need for shading or tone.

"I try to make each shape and each colour enhance every other shape and colour so it's entirely at peace and rest," he says.

Not all art critics welcomed his style in the early years, particularly in Scotland, but Norman ignored them all and stuck to what he felt was right.

Despite being labelled "stubborn" by the press, Norman committed himself to his style of painting and seeing 65 years of it now on display is a tribute to how long he fought for his art.

"His life apart from his family has been in his painting," says son Danny, who describes his father as a fairly reserved man, honest to a fault.

"There have been times when outwardly he has been very successful, but that's never been really why he did it," he says.

"I think his stamina and his resolution are terrific lessons for anybody."

While Danny says his father often jokes about being pigheaded about his work, he says he knows deep down he's not.

"He's just solid in his belief," says Danny. "His sheer bloody mindedness is admirable."

The retrospective of Norman's life work will be on display in Edinburgh until July 23.

"It's an absolutely lovely show," says Danny. "Even I, who have seen the paintings before, could appreciate the journey in a whole new context.

"It's his legacy. It's all him."

Photographs of Norman Gilbert artwork taken by Enzo Di Cosmo