The original posting (with corrected attribution for the mystery photo) -->UPDATE:
Stop the presses -- we have identified the MYSTERY DATE!
It is Brooklyn model Sandy Preston!
See: http://www.elvis-collectors.com/forum/viewtopic.php?f=1&t=64133&p=976186#p976186
Many thanks to FECC's The fool!!
On another topic, the feeling was that this lovely gal seen here is actress Venetia Stevenson:
Elvis and Sandy Preston, Sahara Hotel, Las Vegas - Tuesday, October 22, 1957
But in other photos of Venetia from the period, we seem to see a different woman.
Venetia Stevenson, circa 1956
Tony Perkins, Sophia Loren, Venetia Stevenson - July 1957
Post-premiere party for "The Pride and the Passion," Bali Room, Beverly Hilton, Beverly Hills, CA
Popular Photography, September 1957
Venetia was chosen "Most Photogenic Girl in the World."
Popular Photography, September 1957
Venetia's featured shot.
Venetia and Elvis behind the Strand Theater in Memphis, Thursday, August 8, 1957
They were about to see a midnight screening of "Loving You."
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So, is there anything we have to confirm who Elvis' date was in that October 1957 photo, like a newspaper report? Or perhaps some more photos of this Las Vegas date?