thanks - hope someone can help with a maker. As a quick thought, have you tried Westmoreland - they did have an upper case W as part of their trademarks but am sure it can't be that easy. Understand this pattern is described as hobnail on your side of the pond - Hocking and Fenton in particular made massive amounts of the stuff in milk glass and opalescent colours, with exactly this type of knobbly pattern, though in Europe the word was reserved for the traditional pattern produced by intersection lines. On cut and pressed clear glass, a 'nail head' (hexagonal) shape was produced by a series of intersecting mitre lines, and am sure on your side it was often called cane.
Have you tried any of the States glass forums? - they might be able to help.