|Constable was elected a Royal Academician on 10th February 1829. Although he had at least three major works in his possession, he decided that he wanted to deposit ‘A Boat passing a Lock’ as his Diploma work. The owner of the painting, a friend, James Carpenter, agreed to return the picture to Constable on the condition he received a replacement, preferably a scene of Hampstead Heath. Constable deposited 100 guineas with Sir C. Scott’s banking house as a guarantee that he would paint a picture of the same size by June 1830. He began painting ‘Helmingham Dale’ for Carpenter.|
On 2 April, just before he sent the picture to the Royal Academy exhibition he wrote to Carpenter saying that he would not give him the promised painting after all but forfeit the 100 guineas.
This painting of A Boat passing a Lock depicts a boat ascending the River Stour. It is tied to a post while the lock keeper lowers the level, so that it can enter the chamber before being lifted to the upper level of the river.
The landscape is dominated by the threatening weather conditions on the left. Drawing on his studies of weather effects made in Hampstead and Brighton, Constable convincingly correlates the light falling on the landscape with the configuration of the clouds in the sky and recognises the power of a specific weather condition to animate and give emotional charge to an otherwise seemingly humble, everyday rural scene.