England and Spain's close ties of kinship had bound the royal houses together stretching back to the thirteenth century. In the later sixteenth century, English interest in Spanish culture, history, and politics had intensified precisely during the period when political relations had deteriorated into war. The perception of closeness and filiation ran parallel with enmity and hate. This study demonstrates the complexity of diplomatic and cultural exchange, assimilation, competition, and cooperation that characterized the intricate alliance between England and Spain. It examines England and Spain's shared cultural heritage and the trade agreements and dynastic marriages that had linked them closely by blood. Special attention is given to Philip II's entry into London in 1554 as the new English king, a pivotal moment in the rivalry between the two countries. While popular hostility and fear of Spanish domination certainly contributed to the conflict surrounding the marriage of Philip and Mary, the most difficult issue for the royal couple was the household drama in which the parties on each side sought their own prestige and commercial and political advantage. Perhaps this moment of international diplomatic relations demonstrates above all the delicate balance between honesty and deception, admiration and jealousy, cooperation and rivalry, love and hate that can be found in any close relationship.