Heraldry on the first page of the Psalms text strongly suggests that this Psalter was commissioned by King Edward I for the marriage of his son Alphonso, to Margaret, daughter of Florent V, Count of Holland, which was to take place in 1284. Alphonso died before the wedding, however, and the decoration of the manuscript was left incomplete. Additions were made in the early 14th century, probably before 1316. Perhaps inspired by the story of David and Goliath, which is often depicted in illuminated Psalters, the main scene in the lower margin of this page shows a medieval knight defeating a huge giant. Although the fully-armed knight cannot be intended as a representation of the boy David, who was armed with only a slingshot, the giant wears metal greaves (armour to protect the shins) as in the biblical account.