The Zig Zag i learnt in the Quickstep has the lady starting in Promenade and only turning to face partner at the end. In a Grapevine the lady as well as the man turn to face the other way and back again. I was under the impression this came from English Old Time Dancing. A dance they do called the Balmoral Blues which has been around for ever has in it two Grapevines.