|Wallis Simpson, Duchess of Windsor|
I can understand why the name might not be popular in England, despite the clunky-vintage feel that it gives off people still don't have great feelings towards the woman who took the King from the throne. I am surprised that more girls in America don't have the name as it is the 'fairytale' story of the American commoner marrying the Prince.
It has never charted in either country, nor has it charted anywhere. Not even five girls in 2011 where given the name which is a shame. I know many don't like the name for what it is but I find it charming and if you give a really feminine middle name it should balance out the first. Male names like Eliot are now popular on girls so this name doesn't go off the grain. The variant Wallace however was given to 83 boys in 2011, which really isn't many considering the number of babies born in the US.
For people that like unisex names, this could be another to put on that potential baby name list. I think that it also has a chance with those who like those vintage names like Edith and Sybil. For more information on this name I would recommend reading Upswing Baby Name's article on Wallis.