The famous Italian explorer who sailed under the British flag was John Cabot. Born Giovanni Caboto in Italy, he made his voyages to North America under the commission of King Henry VII in the late 15th century. Cabot is credited with exploring the coast of Newfoundland in 1497, paving the way for future British claims in the New World. His expeditions contributed to the age of exploration and the eventual establishment of British colonies in North America, marking a significant moment in history as European powers expanded their reach into previously unknown territories.