Never heard of them -- but they seem to specialize in auctioning high end handbags. I wouldn't trust a company like that to know anything about autographs.
I remember seeing GWS years ago on Invaluable or Live Auctioneers. Back then it looked to me like they accepted anything for auction offered for consignment to them. I just browsed their current, Dec. 4 sale and their last sale Sept. 4, and it appears that nothing has changed. That's not trustworthy to me.
A number of years ago GWS sold me a FAKE Elvis autograph that was apparently so bad that Graceland took pity upon me and told me that it was fake BEFORE I sent them any money to begin their authentication process.
Having said that, once I sent GWS my correspondence from Graceland, GWS immediately called me, apologized , gave me a full refund and also pledged to give me a “deep discount” on any future purchases I make from them.