When she started out, Billie Holiday was simply the vocalist for Teddy Wilson’s band. The rise of juke box technology, coinciding with her debut, catapulted her to success for the struggling Brunswick label, ensuring its commercial survival and success, and helping to make Teddy Wilson’s name too. These early numbers (still) deserve a wider audience.
But there are other, less-well-known vocalists who also sang with Wilson then. We know the ‘hits’ we hear now from the first few bars, but if you search YouTube, do you find The Hour of Parting? With the vocalist credited?
Who was Boots Castle, who sang The Hour of Parting with Wilson? A beautiful song written by Spoliansky, who fled Germany for London in 1933.
And who was Jean Eldridge, who sang Moonray with Wilson? Was she related to Roy Eldridge, jazz trumpeter?
theproverbial.org 
http://www.allmusic.com/artist/boots-castle-mn0002103676/credits