‘The terms on which the treaty for the freedom of James I. was at last fixed were, on the whole, liberal rather than otherwise. The English demanded, and the Scots agreed to pay, forty thousand pounds sterling—not as ransom, as the use of that obnoxious phrase could not apply to the case of an innocent boy taken without defence in time of truce, but to defray what was delicately termed the expenses of Prince James's support and education. Six years were allowed for the discharge of the sum by half-yearly payments. It was a part of the contract that the Scottish king should marry an English lady of rank; and his choice fell upon Joanna, niece of Richard II. by the mother's side, and by her father, John, duke of Somerset, the granddaughter of the Duke of Lancaster, called John of Gaunt. To this young lady, so nearly connected with the English royal family, the Scottish captive had been attached for some time, and had celebrated her charms in poetry of no mean order, although defaced by the rudeness of the obsolete language. They were married in London; and a discharge for ten thousand pounds, the fourth part of the stipulated ransom, was presented to the Scottish king, as the dowry or portion of his bride. The royal pair were then sent down to Scotland with all respect and dignity, and Murdach, the late regent, had the honor to induct his royal cousin into the throne of his forefathers.’
According to Rampant Scotland, the Treaty of London, releasing James I of Scotland from captivity in England, was signed on December 4, 1423. The text above comes from Walter Scott’s “Scotland”.