The missing picture was sold at auction in 1965 and the foundation is calling on ATG readers to help in the quest.
The charitable trust believes that Evelyn De Morgan (1855-1919) painted a copy of a portrait by artist Frederick Yeates Hurlstone (1800-69).
This Hurlstone picture (shown above) depicts Robert and Elizabeth Buxton and the original by Hurlstone resides in the Norfolk Museums Service.
The trust has recently discovered De Morgan (who was related to Elizabeth Buxton) made a copy which was sold at auction after the death of Margaret Fraser Spencer Stanhope (Evelyn’s mother was a Spencer Stanhope) in 1965.
This picture could have been the first she completed when she was a teenager.
The information about the existence of the painting was found in a sales catalogue of the firm Henry Spencer (a auction house in Retford, Nottinghamshire whose fine arts division became part of Phillips) for Banks Hall, Cawthorne, Barnsley.
It was catalogued as ‘E. de Morgan, after Hurlstone. Charming conversation piece. Elizabeth Julia Spencer Stanhope and Sir Robert Buxton 1834, as children.’
The Barnsley Museums and Archives and The De Morgan Foundation are searching for the 2ft 10in x 3ft 7in (86.5cm x 1.09m) picture.
Sarah Hardy, curator and manager at The De Morgan Foundation, said: “We would like to know its current whereabouts and its journey after the sale. We have been unable to trace who purchased the painting, but we know it definitely sold.”
The charity, created to care for the De Morgan Collection and promote the artists William and Evelyn De Morgan, was set up in 1970. Anyone with information can contact ATG via post or email.
The search for the picture also featured on Art UK's Art detective site.