Conservators at the V&A have discovered a previously unrecorded oil sketch by John Constable concealed beneath the lining of a painting of Hampstead’s Branch Hill Pond.

Ham & High: Self portrait of John Constable circa 1799-1804Self portrait of John Constable circa 1799-1804 (Image: Archant)

The sketch – thought to be of a brick kiln on Hampstead Heath painted around 1821 – is displayed in a special double-sided case at a new exhibition on the painter, which includes his masterpiece The Hay Wain.

Constable: The Making of a Master, which opened at the museum on Saturday, explores the painter’s influences, methods and artistic taste – with examples from his own art collection.

It shows how sketching outdoors in oils to capture the transient effects of light and the weather was central to Constable’s working method.

One example was the Branch Hill Pond painting, among an 1888 bequest of hundreds of sketches, drawings, watercolours and sketchbooks made to the V&A by the artist’s last surviving child, Isabel.

Ham & High: Salisbury Cathedral from the Bishops Ground, painted 1823Salisbury Cathedral from the Bishops Ground, painted 1823 (Image: Images may be reproduced only with written permission of V&A Images, vaimages@vam.ac.uk +44 (0) 207 942 2479)

Painted on a canvas pinned to the lid of the artist’s paint box, it looks west from Jack Straw’s Castle and depicts the sun setting over the pond.

The reverse – discovered beneath the canvas lining with the help of radiography – shows trees against an unsettled sky with a waft of smoke emerging from the kiln.

As V&A senior curator of paintings Mark Evans points out, this attention to the shifting details of nature and landscape meant that “whenever Constable painted a windmill, you felt that the sails would move”.

“Constable didn’t simply approach nature in an unmediated way. The outdoor sketching he used to capture simple effects, a wagon, the changing effects of light, created an extraordinarily vital medium that gave his landscapes their unique authority.”

Ham & High: Stonehenge, 1835Stonehenge, 1835 (Image: Victoria and Albert Museum, London)

Elsewhere in the exhibition, there are other views of Hampstead, where Constable spent his summers from 1819 due to the fragile health of his wife Maria.

Cloud studies made on the Heath include his well-known image of cirrus clouds. Another work shows donkeys and children playing on the Heath, while another was painted above the Vale of Health pond in 1819, and a third is a study of trees with the spire of Hampstead Parish Church just visible. Constable painted Branch Hill Pond several times and exhibited his most accomplished study – shown here – in 1828 at the Royal Academy, where one critic is thought to have hailed it as “a rich and varied piece of colouring imbued all over with the qualities of the English landscape”.

Views of Salisbury Cathedral, Stonehenge, Old Sarum and the artist’s home turf around Dedham Vale and East Bergholt fill the galleries alongside examples of work by the old masters he admired and copied, such as Claude Lorrain’s Landscape with a Goatherd, Gainsborough’s Landscape with a Pool and Rubens’ Moonlight Landscape – copies which Mr Evans says helped Constable “enter into the mind of past masters”.

There are also his full-size sketches for The Hay Wain and The Leaping Horse alongside the finished paintings.

Ham & High: Branch Hill Pond, 1821Branch Hill Pond, 1821 (Image: Archant)

“The greatest inventions are often the most taken for granted,” Evans observes. “The Hay Wain has become one of those exemplary images like the Mona Lisa that are very difficult to look at and imagine how or why they were made.”

He hopes the sketches and studies will explain Constable’s creative journey, help people look afresh at familiar images and rescue a “misunderstood” artist from a reputation as “the painter who launched a thousand tea trays and chocolate boxes”.

Constable: The Making of a Master runs at the V&A until January 11, 2015.