 The portrait has been considered by Erwin Panofsky and some other art historians as a unique form of marriage contract, recorded as a painting.Signed and dated by van Eyck in 1434, it is, with the "Ghent Altarpiece" by the same artist and his brother Hubert, the oldest very famous panel painting to have been executed in oils rather than in tempera.The painting was bought by the National Gallery in London in 1842.