A privy marked cloth worker's personal two disc seal. The particular branch of cloth work is not known but this is a very common type of privy mark with a huge variety of initials on them. See The Crutchley Archive, "One of the books has monogram marks that resemble the notations on lead cloth seals found in the Thames: they may well specify specific cloth as well." Hopefully we will learn more in time.
The find spot is evidence of Britain's cloth trade with Portugal.