In 1664, the infant James became the first Duke of Cambridge and Baron of Dauntsey, titles his uncle, King Charles II, created especially for him.

His baptism took place at St. James's Palace on 22 July, and was performed by Gilbert Sheldon, Archbishop of Canterbury.

[2] His godparents were his uncle King Charles II and his maternal grandfather Edward Hyde, 1st Earl of Clarendon.

[9] By this time it looked unlikely that his uncle would have any legitimate offspring from his barren wife, so Cambridge was already being treated as the heir to the throne after his father.

[12] On 22 May, the Duke of Kendal, who was also sick from convulsions, died at St. James's Palace and Cambridge was transferred to Richmond.

[17] His death on 20 June came as a shock to the nation, who saw it as the doom of the House of Stuart, as the Duke of York was left with no male issue.

His tomb reads (in Latin): "Deposit of the Most Illustrious Prince James Duke of Cambridge & second-born son and Heir of the Most Powerful Prince James Duke of York who in the Queen's Hall of Richmond fell asleep on the twentieth day in his fourth year, AD 1667.

"[19] Pepys wrote that during Cambridge's illness, the English were very concerned of what would happen in the event of his death and disappointed that he did die.

[23] James bore a coat of arms, as a grandson of a British Sovereign, consisting of those of the kingdom, differenced by a label argent of five points ermine.