Basic colour: Green and coppery to almost black.
Pattern colour: Uniform.
Pronotoum: Narrower and flatter than elytra.
Leg colour: Dark brown
Confusion species: Agonum muelleri
The history of this beetle in Britain is an intriguing one and neatly summarised on Mark Telfer's website where it has been assigned the status of missing Carabid: http://markgtelfer.co.uk/beetles/carabidae-ground-beetles/live-carabids-needed-can-you-help/agonum-chalconotum/
RDB Category: Critically endangered
Other notes: Elytral microsculpture almost regularly isodiametric.