John Constable's The Lock set for auction

A painting British artist John Constable kept by his side until his death is to be offered for sale.

The Lock - one of a small group of landscapes known as the Six-Footers - will be put up for sale in December by Sotheby's auction house.

The painting of a bucolic scene on the River Stour in Suffolk is estimated to be worth £8-12m.

It was treasured by the artist who kept it in his studio until his death in 1837.

The picture is one of two versions of the celebrated painting, and the one that the artist retained himself and exhibited throughout his career

Julian Gascoigne, Sotheby's senior British pictures specialist, said: "Constable's absolute mastery as a landscape painter is everywhere in this picture - in the vigour of the almost impressionistic brushwork, in the drama of the clouds and the changing weather, even in the movement of the grass in the fields and the sparkle of water as it cascades through the lock.

"It is one of those pictures that captivates, and the more one looks, the more one sees."

The painting will be exhibited in Hong Kong, New York and Los Angeles, before leading the Old Master & British Paintings Sale on 9 December.