A reader recently sent me a few incredible photos of what appear to be Peal & Co. Windsors from what I would guess are from the 1950s or 1960s - a guesstimate based on the royal warrant stamped on the insole for the late King George VI.
I was initially under the impression that the Windsor was a John Hlustik design, created when Hlustik took over the company in the early 1980s. Somewhere along the way, I heard here and there that the Windsor design was actually inspired by an archived 1930s model. After seeing these shoes, it seems that the latter theory might be the more accurate one.
Of course, if Peal&Co. were producing a Windsor design in the 1950s-1960s, there doesn't appear to have been any legal impediment to Edward Green (and Crockett & Jones, who also have produced a Windsor model for Ralph Lauren at one time or another) using the design. The situation seems similar to the various firms who have produced versions of Nicolas Tuscek's classic "butterfly" loafer design.