A recently discovered painting by Norman Rockwell is to auction at Sotheby's on May 21 with an estimate of $1.5m-2m.

Titled Willie Gillis in Convoy, the piece was found in storage at Gardner High School in Massachusetts after being gifted to the former principal by the artist during the 1950s.

Willie Gillis was the star of a number of Norman Rockwell's paintings

Rockwell's character of Willie Gillis was a regular fixture on the cover of the Saturday Evening Post during the second world war, with this painting the only example from the series that wasn't used.

The proceeds from the sale will be used to set up a foundation for local schools.

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