I really enjoy how Lord Peter seems clever but also a little silly and impetuous, but there's a point in each of Sayers's novels when his serious side comes through, not in a heavy-handed way, but often just as a glimpse. In many ways I find this mask/true self characterization more realistic than the more either/or characters in many books, and it helps to explain why those around him are so devoted to him, even when he acts like an ass.