As dons at Cambridge vote on a new protocol on constraints to free speech, we mark this month the 500th anniversary of the public burning of Martin Luther’s books outside the west door of Great St Mary’s, the university church at Cambridge.

After the 1517 publication of his famous 95 Theses, raging against the Church’s sale of ‘indulgences’ that purported to pardon sin in exchange for money, Luther had been denounced by Pope Leo X in a papal Bull.