Brian- her rejection of the Elphin (Elfin) Knight shows he has no magic power over her.

Yes Richie, I realize that. What is interesting is that the Robb text begins like 'Elfin Knight' but ends like 'Cambric Shirt'. Which might be because one strain was evolving into the other, or that both strains were in general circulation at the same time, and stanzas were transferred from one to the other.