LONDON.- The Tate Gallery has bought a painting by Constable and two other British masterpieces, with help from the Heritage Lottery Fund. John Constable’s Suffolk landscape Fen Lane, East Bergholt, is said to mark a turning point in the painter’s career. The collection has also secured Johan Zoffany’s two portraits of the children of the 3rd Earl of Bute. Tate director Sir Nicholas Serota described the works as "exemplary paintings by two of the most significant figures in British art". "We are thrilled by these acquisitions which will allow us to present these artists in even greater strength," he added. The Constable painting was bought from a private collection for an undisclosed sum - believed to be nearly £3m. The work had been on loan to Tate Britain, but was seen as at risk of auction and export. It belongs to a group of mid-sized canvasses that Constable painted in Suffolk in the open air during the period 1814-17, and depicts a lane that Constable used to use when walking to school in Dedham as a boy. The National Art Collections Fund contributed a total of more than £500,000 to the Tate purchases.