Cloth Seal, Dye Seal, London Dyers Company, WR over Madderbag
Cloth Seal, Dyer's Two-Part Seal, WR, Image & Found by Dave Hiddleston.
Found on Thames foreshore, 18mm.
Blank // madderbag, WR above
The W normally stands for woad but in this case it may be the first initial of the dyer. The madderbag was a general symbol of the London Dyers’ Guild and not as a specific indication of red dye - see Fig.35, London Dyers' Company seals, Geoff Egan, British Museum Occasional Paper 93, Lead Cloth Seals & Related Items in the British Museum. This would date it between the end of the sixteenth and start of the eighteenth century.
See Ciba Review 1: Medieval Dyeing for an image of the full arms of the Worshipful Company of London Dyers and medieval dyeing in general.