MacDonald's speeches, pamphlets and books made him an important theoretician. Historian John Shepherd states that "MacDonald's natural gifts of an imposing presence, handsome features and a persuasive oratory delivered with an arresting Highlands accent made him the iconic Labour leader". After 1931, MacDonald was repeatedly and bitterly denounced by the Labour movement as a traitor to its cause. Since the 1960s, historians have defended his reputation, emphasising his earlier role in building up the Labour Party, dealing with the Great Depression, and as a putative forerunner of the political realignments of the 1990s and 2000s.