Arthur Streeton painted The Murray and the Mountain during the inter-war period. It will be exhibited publicly for the first time since 1944 by Sotheby’s Australia.

Sotheby’s chairman Geoffrey Smith said its magazine and The Border Mail would print the first coloured reproductions of the piece. “We knew it existed, it was consigned to us by the family who acquired it in March 1931,” he said.

“It taps into important environmental issues and protecting the beautiful landscape we have … he considered this image crucial to Australia's national identity.”

The metre-wide painting will go to auction on August 31 at Sydney's InterContinental.