Offered as separate lots and coming from a private collection where they have been for nearly a century, the auction house described the condition of the works as “beautifully preserved”.
The two full-length portraits depict the Prince of Wales (later King Charles II) aged 11 and his sister Mary (the Princes Royal and the mother of the future king, William III) aged nine.
Painted only months before the artist’s death in December 1641, the works were among the artist’s final commissions from his principal patron, Charles I.
Van Dyck had painted another portrait of the Prince of Wales around four years earlier which remains in the Royal Collection, but it is possible that the portraits at Sotheby’s were among the possessions that were left in the artist’s studio in Blackfriars on his death.
Both works were later owned by John Stuart, 6th Marquess Townshend who kept them at Raynham Hall in Norfolk but they were bought by London dealers Agnews when his collection was auctioned by Christie’s in 1904.
At that sale, both paintings were catalogued as by van Dyck’s contemporary Daniel Mytens (c.1590–1647), with the portrait of the Prince of Wales making 460 guineas and the portrait of the Princess Royal making 510 guineas. The former has since been attributed to van Dyck since at least the mid-1950s.
Agnews sold the works to the family of the present owner and they have been passed down by inheritance.
The consignment to Sotheby;s follows the Charles I: King and Collector exhibition held at the Royal Academy in London earlier this year which included some of the artist’s greatest works executed in England, although not these two pictures.
Sotheby’s said the painter had developed his skills at child portraiture from his early years in Genoa and these late works “provide a penetrating likeness of the royal children at a time when their world, and the Stuart monarchy, was on the brink of collapse”.
The portrait of the Prince of Wales shows the subject wearing armour with the ribbon of the Garter – making it more ‘martial and adult’ than the portrait in Royal Collection. Indeed, the outbreak of the English Civil War occurred barely months after this painting was executed, and the heir to the throne then accompanied his father at the battle of Edgehill in October 1642.
The portrait will be estimated at £2m-3m.
The other portrait offered at Sotheby’s depicts nine-year-old Mary shortly after her marriage to Prince William of Orange. She is shown wearing an orange silk dress edged with lace tied with blue ribbon, as well as a ring and large diamond brooch which Sotheby's said was given to her by her husband the day after their wedding.
It is one of three versions of the composition which Sotheby’s believes most likely date from the summer of 1641, when the artist was probably too unwell to finish the picture himself and entrusted his studio to paint the princess’ costume.
The portrait is estimated at £600,000-800,000.
The announcement of this consignments follows rivals Christie’s releasing details of the works from Rugby School in Warwickshire that they will be offering in London the day before.