This is a bombardier beetle that I found in grassland near Dol, Brittany - they're quite rare in UK. It's a small ground beetle which has the ability, when attacked, to release a stream of chemicals from its rear which ignite and explode!
There are several species - does anyone see them regularly?
Brachinus crepitans is the most common in UK.
Better picture at:
http://bugguide.net/images/cache/5QV...2KQK2KEQNK.jpg