It is not every day you stumble upon a long-lost collection of paintings by a renowned artist which have been mysteriously left in an office without a note or explanation.

Key points: Paintings by Pixie O'Harris and her brother in the 1950s were found in a hospital storeroom in 2018

Paintings by Pixie O'Harris and her brother in the 1950s were found in a hospital storeroom in 2018 More paintings which were missing recently appeared without explanation or a note

More paintings which were missing recently appeared without explanation or a note The entire series of 25 paintings will feature in a Pixie O'Harris exhibition in January 2020

That is exactly what happened to Taree resident Janine Roberts when she arrived recently at the Manning Base Hospital on the New South Wales mid north coast.

The paintings were by Pixie O'Harris, a much-loved writer and illustrator of many famous children's stories, including The Babes in the Wood, Cinderella, Little Red Riding Hood and the Pixie O'Harris Nursery Rhyme Book.

Ms Roberts said she knew what the works were as soon as she saw them sitting unattended on a hospital office floor.

"I had goosebumps, I was actually quite emotional about finding these lost paintings," she said.

This painting of water babies was among the collection of paintings which recently appeared in a Manning Base Hospital office. ( ABC News: Emma Siossian )

"When I asked the hospital where they had come from nobody could tell me, they just said they were there waiting in the office when they came to work.

"I like to think there's a bit of Pixie magic happening here."

Pixie O'Harris' paintings often depict fairytale scenes and many find them reminiscent of a more simple time. ( ABC News: Emma Siossian )

Discovery becomes last piece of the puzzle

Ms Roberts already had a vested interest in the Pixie O'Harris art work.

She had gone to the hospital to collect part of a series of the late artist's paintings, after she and fellow Taree resident, Penny Teerman, had unearthed a collection of works in an old hospital storeroom in 2018.

An exhibition of Pixie O'Harris paintings, many which have not been seen for years, will be held at the Manning Regional Gallery in 2020. ( ABC News: Emma Siossian )

The works formed part of a series of 25 paintings which Ms O'Harris and her brother Olaf created for the Manning River District Hospital in 1957.

Ms Roberts said four paintings were still hanging on the hospital walls, and when they found 13 in the hospital storeroom last year, they knew there were still eight other works missing from the collection.

They put a call out on social media to try and find them, but received no clues.

"I think the greatest fear was that they had perhaps deteriorated over the years and gone to the tip," Ms Roberts said.

This painting by Pixie's brother, Olaf O'Harris, was part of the series done for the hospital in Taree. ( ABC News: Emma Siossian )

That was until the day the paintings suddenly appeared at the hospital.

"The day I found them I packed them into the ute very carefully and drove to the art gallery straight away," Ms Roberts said.

"We were all here and it was very exciting unpacking each one and looking at it."

Paintings to go back in the spotlight

Penny Teerman and Janine Roberts (both on the right) with the exhibition curator Sue Mitchell and volunteers who are helping restore the paintings. ( ABC News: Emma Siossian )

The full collection of Pixie O'Harris paintings will feature in an exhibition in Taree in January 2020.

The exhibition curator, Sue Mitchell, said it was rare to have a full series of Pixie and Olaf O'Harris hospital paintings.

"It's like finding lost treasure," she said.

This Pixie O'Harris painting was one of those which had been sitting in an old storage room in the Manning Base Hospital. ( ABC News: Emma Siossian )

"As soon as I look at these works I think of the 1950s.

"Children's books and illustrations in the 1950s had a certain style of them, children are dressed in that style and they are very innocent looking children and it's just delightful."

This Pixie O'Harris painting 'Goodnight' is part of the Manning collection. ( ABC News: Emma Siossian )

The Manning was one of many hospitals, health centres and schools across New South Wales for which Ms O'Harris and her brother painted murals, to try and brighten the atmosphere.

A series of works they did for Sydney's Fairfield Hospital will also be included in the Taree exhibition after a nurse there uncovered some paintings tucked away in a storeroom.

Delicate restoration in good hands

Volunteers are restoring the paintings ahead of the Pixie O'Harris exhibition in January 2020. ( ABC News: Emma Siossian )

Tracey Golds, a former conservator at the National Archives of Australia and State Library of NSW, who now lives in Taree, will lead the paintings' restoration.

"They are very robust paintings in pretty sound condition and we are just doing some basic cleaning of the surface to try and brighten them up a little bit, and a little bit of retouching," she said.

Conservator Tracey Golds is leading the restoration of the paintings and showing other volunteers what to do. ( ABC News: Emma Siossian )

Taree resident Penny Teerman, who is helping lead the project with Ms Roberts, said the paintings were expected to have intergenerational appeal.

"We are hoping children will engage with these paintings, and at the other end of the spectrum, they will appeal to older people, where it's a nostalgia trip for them," she said.

Discovery delights Pixie O'Harris' grandchildren

A portrait of Pixie O'Harris c.1951 by unknown. ( Supplied: National Portrait Gallery )

Some of Pixie O'Harris' grandchildren who live in NSW and Victoria plan to visit the exhibition, including Rowena Evans from Cooma.

"Every time we went to visit our grandparents Pixie was at the dining table which was where she worked," Ms Evans said.

"Even when she didn't have a book in progress she would do oil paintings for herself. Pixie was always creating something and all of the grandchildren were encouraged to be creative.

"Several of us are musicians and artists and other sorts of performers and I think a lot of that comes from encouragement from our grandparents."

Pixie O'Harris was born in 1903 and came to Australia from Wales in 1920. She died in 1991.