Curators of an exhibition by painter John Constable have made fresh discoveries about two portraits.
The paintings are now believed to be of the artist's parents Ann and Golding.
The discoveries were made by two curators conducting research for the exhibition at the National Portrait Gallery in London.
The portraits, now thought to make a pair, have been in the collection at Colchester and Ipswich Museum Service since 1926.
Constable Portraits: The Painter and His Circle opens at the London gallery on Thursday.
The collection of almost 50 portraits will feature oil paintings, sketches and watercolours.
The recent discoveries were made by Anne Lyles, Tate curator and leading authority on the work of Constable, and Martin Gayford, writer and critic, while researching the exhibition.
Painted around 1805, the recently authenticated portrait of Ann Constable is 36 x 28, a format favoured by the artist for portraits early in his career.
The sitter is pictured facing left with a spaniel in her lap. This portrait was painted on canvas supplied by T Brown of Holborn, an artist's merchant known to have been used by Constable.
The sitter in the second portrait has been provisionally re-identified as Golding Constable.
The painting, also the same size, was previously identified as Constable's schoolmaster from Dedham, Dr Thomas Lechmere Grimwood, based on its description in a 1926 Sotheby's sale catalogue as a 'Portrait of the artist's schoolmaster'.
But the subject, exhibition organisers say, bears a strong resemblance to a later portrait of Golding Constable, which belongs to Tate, and the book in his hand is also said to closely resemble the Constable family Bible.
They face complementary directions which suggest they are intended as a pair.
The portrait of Golding is included in the exhibition at the National Portrait Gallery. The portrait of Ann is on display in the Wolsey Art Gallery in Christchurch Mansion, Ipswich.
Emma Roodhouse, art curator at Christchurch Mansion said: "The portrait of John Constable's mother by the artist helps to create another insight into the artist's life and relationships."