Why was James ii son called the warming pan baby?

James II's son was called the "warming pan baby" because there were widespread suspicions that he was not the legitimate child of James and Queen Mary of Modena. Instead, many believed that the baby was secretly brought in to the royal couple's bed in a warming pan to simulate the birth of a legitimate heir. This theory arose during the political turmoil of the Glorious Revolution in 1688, as James II's Catholicism and the birth of a male heir threatened to re-establish Catholic rule in England. The nickname reflected the skepticism surrounding the legitimacy of the child and the political tensions of the time.