A collection of Constable sketches that lay forgotten in a cupboard for 60 years are to go up for auction next month in London.
The 15 drawings were rediscovered after they were brought to Christie's for a routine valuation.
The collection of sketches, including Elm Trees in Old Hall Park, is expected to fetch a combined total of £50,000.
Christie's Old Master and Early British Drawings and Watercolours sale takes place on 3 July.
"Such a rare and interesting group of unrecorded drawings by the master of English landscape has not appeared on the market since 1988," said Christie's Harriet Drummond.
"The drawing of Elm Trees in Old Hall Park is important, as it shows Constable's very precise technique developed to accurately record scale when working direct from nature."
The Elm Trees sketch is a study made using a sheet of glass and ink. It gives an insight into how the final work, now at the Victoria and Albert Museum in London, was created.
Another drawing, The Stour with Stratford St Mary Bridge, includes a letter on the back written by the artist to an unknown correspondent.
John Constable is most noted for The Hay Wain, a rural scene of Flatford Mill on the River Stour that hangs in the National Gallery.
His famous landscapes stemmed from his life in the countryside on the Suffolk-Essex border, often referred to as 'Constable Country'.
He also frequently painted in Salisbury, Brighton and Hampstead, making numerous studies of the clouds over the Heath.
His masterpiece, The Lock, is also being sold at Christie's on 3 July and is estimated to fetch as much as £25 million.
Born in 1776, Constable received little recognition in Britain in his lifetime and was much better known in France.