Spencer Robertson Antiques has dated this piece to the 1930s.
Early Walter Moorcroft initials used a slate blue colour to differentiate it from his father Williams. Walters full signature mark -as seen on the photo- was only used on important pieces, one of pieces for exhibition or limited editions.

The condition is consistent with age and use, it has good overall condition with age related crazing to the yellow wisteria plums on close inspection. There is also a tiny possible chip in the glaze, only visible when the vase is laid down see the purple plum photo.
Spencer Robertson Antiques has dated this piece to the 1930s.
You can view the stock and full dealer information on the Spencer Robertson Antiques Profile Page