Hi ~ welcome to the forums. Can't recall seeing that particular mark before, but E.G. Webster used a number of different marks, many incorporating the Prince of Wales plume, as well as somewhat eccentric lettering similar to the 'W' on yours, the first letter looks like it might be a script 'I' along with something else (Webster was a division of International Silver). American silverplate marks like yours were usually based on British hallmarks, intended to insinuate quality, they often appeared on Sheffield reproductions, but your piece is a Dutch reproduction. The image below, which appears to be your pitcher, is from a 1917 retailer's catalog, the manufacturer is not mentioned, but the items on the page of "Dutch Silver Reproductions" are described as "very heavily silver plated on copper".
~Cheryl
