Joseph Armstrong's early death in 1877 meant that the next phase of motive power design was the responsibility of William Dean who developed express 4-4-0 types rather than the single-driver 2-2-2s and 4-2-2s that had hauled fast trains up to that time.[48] Dean retired in 1902 to be replaced by George Jackson Churchward, who introduced the familiar 4-6-0 locomotives.