Painting by Canadian folk artist Maud Lewis traded for a meal at Irene and Tony Demas’s restaurant could fetch C$35,000

Working out of the kitchen of their small restaurant in Ontario in the 1970s, Irene Demas and her husband Tony soon learned the value of trading their dishes for the talents of local bakers, craftspeople and artisans.

“Everyone supported everyone back then,” said Irene, at the time a bright-eyed chef in her 20s. In exchange for daily fresh flowers, for example, the couple would take soup and a sandwich to the florist next door.

And for an English painter with a predictable palate, the couple struck a deal: they would get a selection of paintings from him and his friends in exchange for grilled cheese sandwiches.

By chance, that deal unwittingly netted them a painting by the acclaimed Canadian folk artist Maud Lewis – a work that nearly five decades later is expected to net more than C$35,000 (US$27,000) when it goes to auction this month.

Nearly every day after it first opened, painter John Kinnear and his wife Audrey enjoyed lunch at the Villa, a restaurant run by the Demases in London, Ontario. And each day, the only meal Kinnear would ever order was a grilled cheese sandwich.

“Mind you, it wasn’t just an ordinary grilled cheese. It was a great sandwich, with a five-year-old cheddar and beautiful bread,” said Irene.

Demas would visit artisan bakeries each morning before the restaurant opened, selecting freshly baked loaves and a “wonderful cheddar that John just loved”.

She’d slather on butter, grilling the slices of whole grain bread until crisp, all for C$2.95. But the repetitive order nonetheless frustrated Demas, who would try to coax her stubborn patron into trying new dishes and daily specials. “He never budged. He just loved that sandwich.”

The first painting the couple received from Kinnear was a watercolour of Jumbo, a famous elephant who was hit and killed by a train in the town of St Thomas, Ontario.

One day, Kinnear came in with a selection of new paintings. Demas emerged from the kitchen and saw half a dozen pieces propped up on the tables and chairs of the restaurant.

“I just sat there in silence for quite a while. I’d never ever seen any art like that before. At first I thought they might be playing or some sort of trick on me,” she said of the bright colours and simple content of the works. “Did a kid do some of these?”

Kinnear told the couple of an artist he’d met out in the province of Nova Scotia, a woman who was “so poor she didn’t have the right things to paint on”, resorting instead to scraps of wood and the leftover paint fishermen used on their boats.

“He felt sorry for her,” said Demas. Kinnear sent Lewis some boards prepped for painting, a handful of which she returned to him with completed works.

Of the selection that day, the only painting that stood out to Demas was one of a black truck. She was pregnant at the time and thought the scene might look nice on her son’s wall, where it has remained until now.

Lewis, who lived most of her life in poverty, was known for her cheery paintings of life in rural Nova Scotia. She often repeated themes, including cats and ice skaters.

“I put the same things in, I never change,” she told a documentary crew in 1965. She painted nearly every inch of the one-room house she shared with her husband, Everett, including the couple’s stove. Lewis’s output dropped in the final years of her life as she developed rheumatoid arthritis. She died in 1970 at age 69.

In the years since, her fame has grown widely and her works increasingly fetch tens of thousands of dollars. A 2013 biopic has only renewed interest and excitement around the unconventional paintings.

“It’s just too bad she didn’t live long enough to really reap the benefits of her art,” said Demas.

With the encouragement of their children, the couple have decided to put the work up for sale, as well as three pieces of correspondence between Kinnear and Lewis, in which she thanks him for his sustained generosity.

“My husband’s 90 and I don’t think I have another 50 years to hang on to it,” she said. “The kids are saying, use the money and travel and just enjoy life.”