Customs Seal, British, Customs and Excise

Customs & Excise Seal, Image by StuE, Found by John GM.
Found on Thames foreshore, 19mm, 4.3g.

Crown // CU(ST)OMS (curved around the top) & (in the centre) EXCISE (curved around the bottom)

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

For duty free UK customs seal see PAS DENO-655F33.