BSG.BS.00509 — Customs Seal, British, Customs and Excise

Found on the Thames foreshore, ?mm.

Crown // CUSTOM(S)

On one side is the British crown and on the other CUSTOMS in a straight line, probably with AND / EXCISE below but both sides have been off-stamped.

A U.K. customs & excise seal.

The Tudor crown indicates it is from a date before 1953 - Wikipedia.