Winter Morning, an oil on panel work Tom Thomson completed in the spring of 1915, is expected to sell for upwards of $800,000. (Joyner Waddington)A striking, snow-covered forest scene by Tom Thomson bearing intriguing inscriptions on the back of the canvas is set for sale in Toronto on Tuesday as Canada's fall auction season gets underway.

Winter Morning, a 20-by-30-centimetre oil painting Thomson completed in 1915, is among the highlights of the 270 lots Joyner Waddington's Canadian Fine Art will offer Tuesday evening.

Expected to fetch between $800,000 and $1 million, the work is rare for a number of reasons.

Aside from the interesting scribbles on the back, Winter Morning is important because it was created by Thomson "at the height of his ability" and — while known to academics and aficionados — it has never before appeared at auction, according to Joyner Waddington vice-president and chief auctioneer Rob Cowley.

'It really is almost the perfect storm in terms of a work by Thomson.'

—Rob Cowley, Joyner Waddington's

"It really is almost the perfect storm in terms of a work by Thomson," Cowley told CBC News on Friday.

"To have so many important details on the back of a work and not only that, but on the back of a work that is so glorious in itself."

Chief among the markings is the iconic Canadian artist's own handwriting.

"For him to sign and title the work, on the back, is incredibly rare. You don't see it very often," Cowley said.

The work also bears a date inscription by Thomson and Group of Seven patron James MacCallum, a note indicating it was at one time in the collection of Thomson's sister, Elizabeth Harkness, as well as the phrase "Not for sale" —scribbled by fellow artist Lawren Harris.

For Harris to have marked the work as such is a huge testament to the importance of the painting, Cowley said.

"It's a dream for us," he said.

Charles Pachter's Dressage, an acrylic and coloured pencil-on-canvas work from 1988, features one of his most iconic images: a saluting Queen Elizabeth II sitting sidesaddle on a moose. (Joyner Waddington)Another piece drawing interest is Charles Pachter's Dressage, a 1988 canvas featuring one of his most enduring images: a saluting, military-dressed Queen Elizabeth II atop a moose. It's estimated it will sell for between $20,000-$30,000.

The painting, also appearing at auction for the first time, comes up for sale amid a revived interest in the Toronto artist's work. Earlier this year, Joyner Waddington set a record for Pachter with the sale of his The Painted Flag ($36,800) and his two recently released children's books, M is for Moose and Canada Counts, have been well-received.

When Pachter first unveiled this image in the 1970s, there was some hostility towards him, with some accusing the artist of mischief despite his assertion that the image was an exploration of the Canadian psyche, Cowley noted.

However, "in terms of pop art in Canada, nobody competes with Pachter," Cowley said, adding that the artist ended up sending a version of the canvas to the monarch and that during a visit to Canada, Prince Charles requested versions for each of his sons, princes William and Harry.

Though recent sales of post-war and contemporary art in the U.S. have had mixed results, Cowley said clients have expressed interest in works at all levels of pricing for Tuesday's sale and that the general feeling is of optimism and confidence.

"When the strongest works are put forward, that's everything you can do as an auction house."