Louis: Lewis, or Louie?

No less an authority than Isobel Strong, Stevenson’s stepdaughter, speaks to this issue. In her  1911 biography Robert Louis Stevenson, she says,

“He was born in Edinburgh on 13th of November, 1850, and christened Robert Lewis Balfour Stevenson. The spelling, but not the pronunciation, of this second name was changed later and the Balfour dropped.”