English or French, 14th century.
Measures 2.1 x 2cm.
The larger matrix is engraved with a griffin rampant, surrounded by the owners name ’S. MARTI LAMBERT’.
The smaller matrix is too degraded to make out its image.
Similar bronze seals can be found in the Portable Antiquities Database, Unique ID’s: LIN-25ACF8 and BH-C2D233.
https://finds.org.uk/database/artefacts/record/id/996584
https://finds.org.uk/database/artefacts/record/id/568494