Let us know what you think and join the conversation at the bottom of this article.Fergusson completed the watercolour "Boys at the High School, Edinburgh on a piece of paper between 1887 and 1890 when he was a pupil at The Royal High School.
The Leith-born artist, who may have been just 13-years-old at the time, painted three boys in uniform chatting outside the school -one of the oldest in the world – which was then located near Calton Hill.
The 130-year-old painting, which has been in a private collection for nearly 50 years, will be offered at Bonhams' Scottish Art sale on May 13. The 50x42.5cm artwork is estimated at £4000-6000.
May Matthews, Bonhams' specialist in Scottish Art, said the watercolour showed the painter's "natural talent, although it was an example of "tone" rather than the colour, shape and form for which the artist would later become renowned.
She said: "This is the earliest known work by Fergusson, and shows his pals at the school gates at The Royal High School in Edinburgh.
"It's a lovely picture, painted when he was still a lad, and shows he had natural talent."
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J.D. Fergusson was born in Leith in 1874, the eldest of four children in a family of successful wine merchants originally from the Pitlochry area, in Perthshire.
After leaving school, Fergusson trained briefly as a naval surgeon before studying at an art school in the Scottish capital. In 1898 he travelled to Paris to study at the Louvre and radically changed his approach to art.
Fergusson only returned to live permanently in Scotland in 1939, when he settled in Glasgow until his death in 1961. Fergusson, along with fellow Scottish Colourists S.J. Peploe, F.C.B. Cadell and Leslie Hunter, have achieved international acclaim in recent years.
Ms Matthews added: "Boys at the High School is a beautiful emotionally connected sketch. Fergusson may have been thinking about his future career at that stage, but it would be a few more years before he would formulate his ideas about colour, shape and form which is really what he went on to create for the first time in Scottish art history."
The Royal High School can trace its roots back to the 12th century and has been located at several sites in Edinburgh including Calton Hill (1829-1968) and its current home in the city's Barnton district.
Famous former pupils include telephone inventor Alexander Graham Bell; poet and novelist Sir Walter Scott; Chariots of Fire actor Ian Charleston; and comic Ronnie Corbett.
The Scottish Art Sale also includes a ‘near-perfect’ oil painting of apples and pears by Colourist Samuel John Peploe , which could fetch £180,000.
Peploe completed "Still Life with Tureen and Fruit" in 1926, when he was working in studios between Edinburgh and the South of France.
The artist, who was 55 years old at the time, was famously "obsessed" by creating the perfect still life and spent days setting up and rearranging objects for his compositions.
Peploe, born in Edinburgh in 1871, was the eldest of the four Scottish Colourists, who also included Fergusson, George Leslie Hunter and Francis Campbell Boileau Cadell.
He was influenced from an early age by the Dutch masters who graced the walls of the Scottish National Gallery and in 1910 moved to Paris.
Peploe transformed and defined his own artistic style before returning to Edinburgh in 1912. He became renowned for his still life compositions, which he planned and executed meticulously.
In a letter of 1929, just three years after he painted "Still Life with Tureen and Fruit", Peploe wrote: "There is so much in mere objects, flowers, leaves, jugs, what not – colours, forms, relations - I can never see the mystery coming to an end."
A total of 21 paintings and sketches by the four Scottish Colourists feature in Bonhams' Scottish Art Sale, with a total value of more than £680,000.
Other highlights include "Anemones in a Yellow Vase" by George Leslie Hunter, valued at £50,000-80,000; and Fergusson's "Paris Street Scene", which is expected to fetch £25,000-30,000. Cadell's watercolour sketch "Tying the Rick" is estimated at £5000-8000.