Cloth Seal / Tag, Searchers Seal, Image & Found by Derfel.
Found on Thames foreshore, 35x24mm.
8 / R.MILARD / 5 = // blank
Possibly a development of the more modern searchers / inspectors cloth seal although it could possibly be some form of name tag unconnected to the cloth industry. However see R:BEAZER seal at the bottom of the DE West Frisiae 4 page.