Who sang Deep Purple in 1940s?

Bing Crosby I believe. The song was Ritchie Blackmore's grandmother's favourite song, which is how the band Deep Purple got their name.

Well, actually, there were several versions of the song recorded between 1933 and the early 1980s, but Bing never had a big hit with it. It was, however Ritchie's grandmother's favorite song, as noted.