Before he was the worlds foremost Catholic biographer, Joseph Pearce was a leader of the National Front, a British-nationalist, white-supremacist group. Before he published books highlighting and celebrating the great Catholic cultural tradition, he disseminated literature extolling the virtues of the white race, and calling for the banishment of all non-white from Britain.

Pearce and his cohorts were at the center of the racial and nationalist tensions-often violent-that swirled around London in the late-1970s and early 80s. Eventually Pearce became a top member of the National Front, and...