Reacting sharply against the whiggish thesis that religious tolerance was a heritage of the Enlightenment, revisionist scholars have pointed to the many pragmatic concessions people made to tolerate those of other faiths prior to the eighteenth century. While they have underscored the contingent relationship of tolerance with neighbourliness in many important case studies, the historiography portrays early modern London as an essentially intolerant society for the city’s Catholics and a church on the margins. Through an examination of London’s embassy chapels reflected in vicious anti-Catholic polemic, this article argues that tolerance was not lacking in Jacobean London. It additionally shows how ambassadors’ chapels sustained a vibrant and visible form of Counter-Reformation Catholicism in the capital. Finally, it assesses how contemporaries connected both of these issues to tensions surrounding the ‘king’s two bodies’ and the execution of the royal prerogative. While this places London’s Catholics at the heart and centre of Jacobean religio-political tensions, the article concludes that it is ultimately the circular relationship between tolerance and intolerance that is key to understanding why a contested form of corporate Catholicism survived in the very heart of England’s Protestant kingdom.